Systems and methods for anaerobic digestion of biomaterials

ABSTRACT

Systems and methods for performing anaerobic digestion of biomaterials using a clarifier, a batch reactor, and/or a digester are disclosed. The clarifier performs pretreatment processing of biomaterial to improve anaerobic digestion. The batch reactor and/or the digester are coupled to the clarifier and are configured to digest the processed biomaterial. A control system for an anaerobic digestion process includes a flow control system, a temperature control system, and a totalization system. The flow control system controls the flow of biomaterial and the delivery of chemical agents to the biomaterial based on conductivity, temperature, pressure, and/or composition of the biomaterial. The temperature control system includes a heat source and heat exchangers that control the temperature of the biomaterial. The totalization system senses the volume of biomaterial in at least one stage of an anaerobic digestion process and a controller controls the flow control system based upon the sensed volume of biomaterial.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/360,669, filed on Jan. 28, 2012, now U.S. Pat.No. 8,308,946, which is incorporated herein by reference in itsentirety.

BACKGROUND

1. Technical Field

The present disclosure relates to an anaerobic digestion systemincluding one or more digesters. More specifically, the presentdisclosure is directed to a clarifier for pretreatment processing ofbiomaterials to improve anaerobic digestion, a batch reactor fordigesting the processed biomaterials, and a digester. The presentdisclosure also provides for an active monitoring system with dynamicmaterial and gas flow control.

2. Background of Related Art

Anaerobic digestion is the breakdown of organic material bymicroorganisms in the absence of oxygen and has been used for theprocessing and treatment of primarily organic waste to producenon-hazardous, and sometimes beneficial, products.

The microbiology of anaerobic digestion can be generally described ascomprising three broad trophic groups, which digest organic materials insequence. The first group, the hydrolytic and fermentative bacteria,contains both obligate and facultative anaerobes, and removes smallamounts of oxygen that may be introduced into the digester with thewaste influent. By hydrolysis, this group initially breaks down the morecomplex molecules (e.g., cellulosics, starch, proteins, lipids, etc.)into smaller units (e.g., amino acids, sugars, and fatty acids). Then,by a process of acidification, this group uses these smaller compoundsto produce formate, acetate, propionate, butyrate, hydrogen, and carbondioxide. These acidic products are then available for the next trophiclevel. In many digesters, the rate-limiting step is the hydrolysis ofcomplex molecules, particularly the polysaccharides.

The second trophic group comprises hydrogen-producing acetogenicbacteria or proton-reducing bacteria. By a process of acetification,this group makes acetate from compounds such as fatty acids, butyrate,formate, and propionate.

The third trophic group comprises the methanogenic bacteria, whichconvert compounds such as acetate into methane gas and carbon dioxide ina process called methanogenesis.

Conventional anaerobic digestion takes place within one or moredigesters as the organic material is processed by the microorganismsdescribed above. There is a continual need to provide for more efficientanaerobic digestion systems.

SUMMARY

In one aspect, the present disclosure features an anaerobic digestionsystem including a clarifier, a batch reactor, and a digester. Theclarifier receives a first biomaterial and a second biomaterial, andundertakes pretreatment processing of the first and second biomaterialsto form a digestate. The batch reactor is coupled to the clarifier. Thebatch reactor includes a plurality of chambers in fluid communicationwith each other that provide for the flow of the digestate through thebatch reactor. The batch reactor also includes a digestion substratedisposed within the plurality of chambers. The digester is coupled tothe batch reactor and is configured to receive the digestate from thebatch reactor.

Each of the clarifier, the batch reactor, and the digester may includeat least one gas sample port configured to withdraw gas from theclarifier, the batch reactor, and the digester. The gas sample ports maybe coupled to a gas analyzer configured to analyze gas withdrawn fromthe clarifier, the batch reactor, the digester, or combinations thereof.

The anaerobic digestion system may further include a gas and mass flowcontrol assembly configured to control a flow of gases and the digestatebetween the clarifier, the batch reactor, and the digester based on thegas analysis by the gas analyzer.

The first biomaterial may include a chemical oxygen demand per literfrom about 1 gram to about 3,000 grams and volatile solids content perliter from about 1 gram to about 200 grams. The second biomaterialincludes organic volatile solids, which may be loaded into the clarifierat a rate of from about 0.01 grams of organic volatile solids perliter-day to about 250 grams of organic volatile solids per liter-day.

The anaerobic digestion system may further include a heat source coupledto the clarifier, the batch reactor, the digester, or combinationsthereof. The anaerobic digestion system may further include a gas andmass flow control assembly that withdraws at least one gas from theclarifier, the batch reactor, or the digester, and provides at least onegas to the heat source as a source of fuel.

Each of the clarifier, the batch reactor, and the digester may includeat least one probe that measures at least one of pH oroxidation-reduction potential. The probes may be coupled to a chemicalfeed control assembly including at least one chemical supply tank. Thechemical feed control assembly controls the release of a chemical agentstored therein.

The anaerobic digestion system may further include one or morebiological reactors containing one or more microorganisms. Themicroorganisms may include a hydrolytic microorganism and an acidogenicmicroorganism. The one or more biological reactors may supply one ormore of the microorganisms to the clarifier.

The batch reactor may contain one or more acetogenic microorganisms andthe digester may contain one or more methanogenic microorganisms. Thechambers in the batch reactor may be arranged in a serpentineconfiguration. The digester may be coupled to the clarifier and mayrecirculate the digestate through the clarifier.

In another aspect, the present disclosure features a method foranaerobic digestion. According to the method, a first biomaterial and asecond biomaterial are received into a clarifier, in which pretreatmentprocessing of the first and second biomaterials is selectivelyundertaken to form a digestate. The digestate is then passed through abatch reactor that includes a digestion substrate disposed in aplurality of chambers that are in fluid communication with each other.After the digestate passes through the batch reactor, the digestate istransferred to a digester. One or more gases generated during anaerobicdigestion are removed from the clarifier, the batch reactor, or thedigester and are supplied to the digester.

The plurality of chambers in the batch reactor may be arranged in aserpentine configuration. The digestion substrate disposed in theplurality of chambers of the batch reactor may include at least oneacetogenic microorganism. Also, the digester may include at least onemethanogenic microorganism.

The method for anaerobic digestion may further include pasteurizing thefirst and second biomaterials. The first biomaterial may be contactedwith at least one acidogenic microorganism and the second biomaterialmay be contacted with at least one hydrolytic microorganism within theclarifier.

The first biomaterial may include a chemical oxygen demand per literfrom about 1 gram to about 3,000 grams and volatile solids content perliter from about 1 gram to about 200 grams. The second biomaterial mayallow for a solid organic loading rate from about 0.01 grams of volatilesolids per liter-day to about 250 grams of volatile solids perliter-day.

In yet another aspect, the present disclosure features an anaerobicdigestion batch reactor. The anaerobic digestion batch reactor includesa plurality of chambers to provide for the flow of a digestate throughthe plurality of chambers, a digestion substrate disposed within atleast one of the plurality of chambers, and one or more flow controlmechanisms. The one or more flow control mechanisms may include acontrol valve or a sluice gate that controls a flow of the digestatebetween at least two chambers of the plurality of chambers. Thedigestion substrate includes one or more microorganisms. The one or moremicroorganisms may be a hydrolytic, saccharolytic, proteolytic,lipolytic, nitrate reducers, nitrite reducers, iron reducers, manganesereducers, sulfate reducers, acidogenic, acetogenic, methanogenic,organic acid fermenters, alcohol fermenters, or any combination of thesemicroorganisms.

The anaerobic digestion batch reactor may further include a heat sourcecoupled to the plurality of chambers. The plurality of chambers mayinclude a first portion comprising a first microorganism that ismaintained at a first temperature by the heat source and a secondportion comprising a second microorganism that is maintained at a secondtemperature. The plurality of chambers may include a first portionincluding at least one hydrolytic microorganism that is maintained at afirst temperature by the heat source, a second portion including atleast one acidogenic microorganism that is maintained at a secondtemperature, a third portion including at least one acetogenicmicroorganism that is maintained at a third temperature, and a fourthportion including at least one methanogenic microorganism that ismaintained at a fourth temperature.

The plurality of chambers may include at least one gas sample port fromwhich to withdraw gas. The gas sample ports may be coupled to a gasanalyzer that analyzes gas withdrawn from the plurality of chambers. Theanaerobic digestion batch reactor may further include a gas and massflow control assembly that controls the flow of gases and digestatebetween the plurality of chambers based on the gas analysis of the gasanalyzer.

The first biomaterial may include a chemical oxygen demand per literfrom about 1 gram to about 3,000 grams and volatile solids content perliter from about 1 gram to about 200 grams. The second biomaterial mayinclude a material that allows for a solid organic loading rate fromabout 0.01 grams of volatile solids per liter-day to about 250 grams ofvolatile solids per liter-day.

The plurality of chambers of the anaerobic digestion batch reactor mayinclude at least one probe that measures at least one of pH oroxidation-reduction potential. The probes may be coupled to a chemicalfeed control assembly including at least one chemical supply tank. Thechemical feed control assembly controls release of a chemical agentstored in the chemical feed control assembly. The plurality of chambersmay be arranged in a serpentine configuration.

In yet another aspect, the present disclosure features an anaerobicdigestion batch reactor. The anaerobic digestion batch reactor includesa plurality of chambers including a first portion and a second portion.The plurality of chambers is in fluid communication with each other andprovide for the flow of digestate through the plurality of chambers. Theanaerobic digestion batch reactor also includes a digestion substratedisposed within the first and second portions of the plurality ofchambers. The first portion of the plurality of chambers includes atleast one first microorganism and the second portion of the plurality ofchambers includes at least one second microorganism. The anaerobicdigestion batch reactor also includes at least one flow controlmechanism, such as a control valve or a sluice gate that controls a flowof the digestate between the first and second portions of the pluralityof chambers.

The at least one first microorganism and the at least one secondmicroorganism may be different and may include a hydrolytic,saccharolytic, proteolytic, lipolytic, nitrate reducers, nitritereducers, iron reducers, manganese reducers, sulfate reducers,acidogenic, acetogenic, methanogenic, organic acid fermenters, alcoholfermenters, or any combination of these microorganisms.

The anaerobic digestion batch reactor may further include a heat sourcecoupled to the plurality of chambers. The first portion of the pluralityof chambers may be maintained at a first temperature by the heat sourceand the second portion of the plurality of chambers may be maintained ata second temperature by the heat source. Each of the first and secondportions of the plurality of chambers may include at least one gassample port from which to withdraw gas. The gas sample ports are coupledto a gas analyzer that analyzes gas withdrawn from each of the first andsecond portions of the plurality of chambers. The anaerobic digestionbatch reactor may further include a gas and mass flow control assemblythat controls the flow of gases and digestate between the first andsecond portions of the plurality of chambers based on the gas analysisof the gas analyzer.

Each of the first and second portions of the plurality of chambers mayinclude at least one probe that measures pH, oxidation-reductionpotential, or both. The probes may be coupled to a chemical feed controlassembly including at least one chemical supply tank. The chemical feedcontrol assembly may control release of a chemical agent stored in theat least one chemical supply tank to maintain at least one of pH oroxidation-reduction potential within the first portion of the pluralityof chambers at a first value and the second portion of the plurality ofchambers at a second value. The pH within the first and second portionsof the plurality of chambers may be maintained from about 3 to about 10.Also, the oxidation-reduction potential within the first and secondportions may be maintained from about −500 mV to about +50 mV.

In yet another aspect, the present disclosure features an anaerobicdigestion clarifier. The anaerobic digestion clarifier includes a firstreceptacle and a second receptacle that are in communication with eachother and that are interconnected by a first opening. The firstreceptacle receives a first biomaterial and the second receptaclereceives a second biomaterial. The first opening is disposed above afloor of the first receptacle to allow for retention of solid contentswithin the first receptacle while draining liquid contents into thesecond receptacle via the first opening.

The first and second receptacles of the anaerobic digestion clarifiermay be coupled to a heat source that maintains the first receptacle at afirst temperature and the second receptacle at a second temperature topasteurize the first and second biomaterials. The first and secondtemperatures may be the same or different and may be from about 25° C.to about 60° C.

The anaerobic digestion clarifier may further include a second openinginterconnecting the first and second receptacles and a pump coupled tothe second opening. The first and second openings may be opened and thepump may be activated to selectively mix the first and secondbiomaterials within the first and second receptacles to form adigestate. The anaerobic digestion clarifier may further include a thirdreceptacle in fluid communication with at least one of the firstreceptacle or second receptacle. The third receptacle may receive thedigestate. A floor of the third receptacle may be disposed below thefloor of at least one of the first receptacle or second receptacle toenable mixing of digestate as it flows from at least one of the firstreceptacle or second receptacle to the third receptacle.

The anaerobic digestion clarifier may further include a first biologicalreactor coupled to the first receptacle and including at least one firstmicroorganism, and a second biological reactor coupled to the secondreceptacle and including at least one second microorganism. The at leastone first organism may be an acidogenic microorganism. The at least onesecond organism may be a hydrolytic microorganism. The second biologicalreactor may be coupled to the third receptacle and may be configured toreceive the digestate.

In yet another aspect, the present disclosure features a method foranaerobic digestion. According to the method, a first biomaterial isreceived at a first receptacle of a clarifier and a second biomaterialis received at a second receptacle of the clarifier. The first andsecond biomaterials are then pasteurized at a temperature from about 40°C. to about 250° C. for about 3 minutes to about 12 hours. Also, thefirst biomaterial is placed into contact with at least one firstmicroorganism and the second biomaterial is placed into contact with atleast one second microorganism within the clarifier. Then, the first andsecond biomaterials are selectively mixed within the first and secondreceptacles to form a digestate. The first and second biomaterials maybe pasteurized by injecting steam into the first and secondbiomaterials.

According to the method for anaerobic digestion, at least one firstmicroorganism may be stored within a first biological reactor and the atleast one second microorganism may be stored within a second biologicalreactor. The first biological reactor may be coupled to the firstreceptacle and the second biological reactor may be coupled to thesecond receptacle. The first biomaterial may include fats-oils-greases(FOG), slaughterhouse waste, winery waste, municipal waste, animalmanures, domestic sludge waste, coffee waste water, chemical waste, andcombinations thereof, and may include a chemical oxygen demand per literfrom about 1 gram to about 3,000 grams and volatile solids content perliter from about 1 gram to about 200 grams. The at least one firstmicroorganism may be an acidogenic microorganism. The second biomaterialmay include energy crops, post-harvest crops, post-consumer waste,non-hazardous laboratory waste, construction and demolition waste,post-consumer waste, animal by-products, food waste, residual waste,forestry waste, municipal solids, and combinations thereof, and mayallow for a solid organic loading rate from about 0.01 grams of volatilesolids per liter-day to about 250 grams of volatile solids perliter-day. The at least one first microorganism may be a hydrolyticmicroorganism.

The method for anaerobic digestion may further include transferring thedigestate from at least one of the first receptacle or second receptacleto a third receptacle and transferring the digestate from the thirdreceptacle to the second biological reactor.

In yet another aspect, the present disclosure features an anaerobicdigester. The anaerobic digester includes an enclosed reactor thatcollects at least one gas generated during anaerobic digestion of thedigestate. The anaerobic digester also includes a flexible inlet thatsupplies digestate into the enclosed reactor and that floats at leastpartially on the surface of the digestate within the enclosed reactor.The anaerobic digester further includes at least one gas diffuserdisposed within the reactor that recirculates the at least one gasthrough the enclosed reactor. The enclosed reactor may include a floor,a plurality of walls, and a stretchable cover. The anaerobic digestermay further include at least one circulation piping loop coupled to aheat source that maintains a temperature within the enclosed reactorfrom about 25° C. to about 60° C. The flexible inlet may include aflexible portion coupled to a source of the digestate and a rigidportion including first and second segments disposed in a Y-shapedconfiguration with respect to the flexible portion. The rigid outletportion projects the digestate stream in at least two directions.

In yet another aspect, the present disclosure features an anaerobicdigester. The anaerobic digester includes an enclosed reactor, a gastake-off in fluid communication with the enclosed reactor, at least onescrubber coupled to the gas take-off, and a flow control mechanism. Theat least one scrubber removes at least one undesirable gas includinghydrogen sulfide, ammonia, carbon dioxide, nitrogen, and anycombinations of these undesirable gases. The flow control mechanismrecirculates the gas output from the scrubber into the enclosed reactor.

The gas take-off may provide the at least one gas as a source of fuel toa heat source configured to maintain the reactor at a temperature fromabout 25° C. to about 60° C. The anaerobic digester may further includeat least one methanogenic microorganism.

In yet another aspect, the present disclosure features a method foranaerobic digestion. According to the method, a digestate is suppliedinto an enclosed reactor and at least one gas collected within theenclosed reactor is withdrawn. Then, the at least one gas isrecirculated within the enclosed reactor through at least one diffuser.The enclosed reactor may include at least one methanogenicmicroorganism.

The method for anaerobic digestion may further include maintaining atemperature within the enclosed reactor from about 25° C. to about 60°C. The method may further include supplying the at least one gas as asource of fuel to a heat source configured to maintain the enclosedreactor at a temperature from about 25° C. to about 60° C. The methodmay further include passing the at least one gas through at least onescrubber to remove at least one undesirable gas including hydrogensulfide, ammonia, carbon dioxide, and any combination of theseundesirable gases.

The digestate may be supplied to the enclosed reactor by injecting thedigestate into the enclosed reactor through a flexible inlet. Theflexible inlet may include a flexible portion and a rigid portion. Theflexible portion is coupled to a source of the digestate. The rigidportion includes first and second segments in a Y-shaped configurationwith respect to the flexible portion. In this configuration, the rigidportion projects the digestate stream in at least two directions.

In yet another aspect, the present disclosure features a control systemfor a digestion system. The control system includes a flow controlsystem, at least one sensor, and a controller. The flow control systemincludes a first flow control mechanism that control the flow ofmaterial through the digestion system and a second flow controlmechanism that controls the flow of at least one chemical agent to thematerial. The at least one sensor senses at least one property of thematerial including ORP, pH, temperature, pressure, composition, or anycombination of these properties. The controller controls the flowcontrol system based on the at least one property of the material.

The controller may be a logic controller, a programmable logiccontroller, a logic circuit, a field programmable gate array, or acomputer. The flow control system may include a movement control systemthat control the flow rate of material in the digestion system and adirectional control system that control the flow direction of thematerial in the digestion system.

The control system may further include a temperature control system thatcontrols the temperature of the material. The digestion system mayinclude a collection tank, a clarifier, a batch reactor, a biologicalreactor, and a digester. The flow control system may include adirectional control system that controls the flow of material from theclarifier to both the digester and the batch reactor simultaneously. Theclarifier and the batch reactor may each include a level sensor and theflow control system may transfer material from the clarifier to thebatch reactor based on a material retention period for the clarifier andthe batch reactor and the material levels measured by the level sensors.

The digestion system may further include an influent collection tankhaving a level sensor, the clarifier and the batch reactor each having alevel sensor. The movement control system may transfer biomaterial fromthe influent collection tank to the clarifier based on a materialretention period for the clarifier and/or the batch reactor and materiallevels measured by the level sensors. The clarifier and the batchreactor may each include a level sensor and the directional controlsystem may control the direction of material flow from the clarifierbased on a material retention period for the clarifier and/or the batchreactor and the material levels measured by the level sensors. Thedigestion system may include a clarifier and a batch reactor.

The first flow control mechanism may be a pump, a blower, a valve, or agate. The gate may be a fluid-actuated gate and the valve may be afluid-actuated valve. The flow control system may further include afluid pump operably coupled to the fluid-actuated gate and thefluid-actuated valve.

The flow control system may recirculate material through at least oneportion of the digestion system. The flow control system may alsorecirculate material between the clarifier and the digester. The flowcontrol system may further continuously cycle between periods ofrecirculation and non-recirculation. The flow control system may furtherrecirculate material through the batch reactor or recirculate gasthrough the digester.

The temperature control system may include a temperature sensor thatsenses the temperature of the material and a temperature sensor thatsenses a temperature of a fluid flowing through a heat exchangerdisposed within the material. The temperature control system may controlthe temperature of the fluid flowing through the heat exchanger based onthe temperatures measured by the temperature sensors.

The material may include gas and the flow control system may transferthe gas from a reactor to another location based on at least one of thecomposition of the gas and the pressure of the gas. The material mayinclude gas and the flow control system may transfer gas from a reactorto a gas storage vessel, a flare, or an evacuation vent based on atleast one of the composition of the gas and the pressure of the gaswithin the reactor.

The logic controller may control the amount of gas produced by theanaerobic digestion system to meet the heat loads and electrical loadsof the anaerobic digestion system or external systems by controlling theflow control system and the temperature control system. The controlsystem may include a totalization system including a gas pressure sensorthat measures gas pressure. The flow control system may control theamount of a gas transferred from a reactor of the anaerobic digestionsystem based on at least one of the gas pressure measured by the gaspressure sensor and the composition of the gas.

The temperature control system may include a material heat exchangerfluidly coupled to an output of a batch reactor and fluidly coupled toan output of the collection tank. The material heat exchanger may enablethe transfer of heat from a material output from the batch reactor to amaterial output from the collection tank.

In yet another embodiment, the present disclosure features a controlsystem for an anaerobic digestion process. The control system includes atotalization system that senses the volume of material in at least onestage of the anaerobic digestion process including hydrolysis,acidogenesis, acetogenesis, and methanogenesis, or any combination ofthese stages. The control system also includes a processor thatdetermines a total energy potential of the material based on the sensedvolume and composition of the material.

The control system may further include a flow control system thatcontrols the flow of material through the digestion system and acontroller that controls the flow control system based on the totalenergy potential of the material. The flow control system may control atleast one of the amount of gas transferred between reactors of theanaerobic digestion system, the amount of gas re-circulated within areactor of the anaerobic digestion system, the amount of gas convertedto heat, the amount of gas converted to electricity, or the amount ofgas flared.

The totalization system may include a conductivity meter and a pressuresensor coupled to a reactor. The flow control system may retain materialwithin the reactor when the conductivity of the material measured by theconductivity meter has not reached a predetermined conductivity within aretention period. The flow control system may enable transfer of thematerial to another reactor when the conductivity measured by theconductivity meter reaches the predetermined conductivity. The flowcontrol system may control the flow of a chemical agent into the reactorbased on the conductivity of the material measured by the conductivitymeter. The conductivity meter may include an ORP meter and a pH meter.The totalization system may further include a total organic carbonanalyzer and/or a gas chromatograph.

In yet another aspect, the present disclosure features a control systemfor an anaerobic digestion system. The control system includes a firstflow control mechanism that controls the flow of at least one chemicalagent to a material contained within a clarifier to form a digestate.The control system also includes a second flow control mechanism thatcontrols the flow of digestate from the clarifier to a batch reactor.The control system also includes a third flow control mechanism thatcontrols the flow of digestate through the batch reactor, which includesa plurality of chambers that are in fluid communication with each other.

The control system may further include a fourth flow control mechanismthat removes at least one gas generated during anaerobic digestionwithin the clarifier and the batch reactor. The fourth flow controlmechanism may further provide the at least one gas to a digester. Thecontrol system may further include a fifth flow control mechanism thattransfers the digestate from the batch reactor to the digester. Thecontrol system may further include a sixth flow control mechanism thattransfers the digestate from the digester to the clarifier.

In yet another aspect, the present disclosure features a method ofcontrolling a digestion system. According to the method, one or moreproperties of a material in the digestion system is sensed. The one ormore properties includes ORP, pH, temperature, pressure, composition,and combinations thereof. Then, the flow of one or more chemical agentsto the material is controlled. The flow of the material through thedigestion system is also controlled based on the one or more propertiesof the material.

The flow of the material may include the flow rate of the material andthe flow direction of the material. The digestion system may be aclarifier, a batch reactor, a digester, and combinations thereof.

The method may further include determining the volume of the materialand controlling the flow of the material based on the volume of thematerial. The method may still further include determining a totalenergy potential of the material based on the volume of the material andthe composition of the material, and controlling the flow of thematerial through the digestion system based on the total energypotential of the material.

Controlling the flow of the material may include controlling the flow ofgas from the digestion system to a gas storage vessel, a flare, or anevacuation vent based on at least one of the composition of the gas andthe pressure of the gas within the digestion system. Controlling theflow of the material may alternatively include controlling the amount ofgas produced by the digestion system to meet heat loads and electricalloads of the digestion system or external systems. Controlling the flowof the at least one chemical agent may include controlling the flow ofone or more chemical agents based on one or more properties of thematerial including ORP, pH, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described herein withreference to the drawings wherein:

FIG. 1 is a schematic diagram of an anaerobic digestion system accordingto the present disclosure;

FIG. 2A is a plan, cross-sectional view of an influent collection tankaccording to the present disclosure;

FIG. 2B is a side, cross-sectional view of the influent collection tankof FIG. 2A as taken along section 2B-2B of FIG. 2A;

FIG. 3A is a plan, cross-sectional view of a clarifier according to thepresent disclosure;

FIGS. 3B and 3C are side, cross-sectional views of the clarifier of FIG.3A taken along section lines 3B-3B and 3C-3C, respectively;

FIG. 4 is a schematic diagram of a heat source system according to thepresent disclosure;

FIG. 5 is a schematic diagram of a chemical feed controller according tothe present disclosure;

FIG. 6A is a plan, cross-sectional view of a batch reactor according tothe present disclosure;

FIGS. 6B and 6C are side, cross-sectional views of the batch reactor ofFIG. 6A taken along section lines 6B-6B and 6C-6C, respectively;

FIG. 7 is a plan, cross-sectional view of the batch reactor of FIG. 6Aillustrating digestate flow according to the present disclosure;

FIG. 8 is a plan, cross-sectional view of the batch reactor of FIG. 6Aincluding digestion substrate piping according to the presentdisclosure;

FIG. 9 is a plan, cross-sectional view of the batch reactor of FIG. 6Aincluding heat exchange piping according to the present disclosure;

FIG. 10 is a plan, cross-sectional view of a digester according to thepresent disclosure;

FIG. 11 is a side, cross-sectional view of the digester of FIG. 10;

FIG. 12 is a plan, cross-sectional view of the digester of FIG. 10including heat exchange piping according to the present disclosure;

FIG. 13 is a schematic diagram of a gas and mass flow control systemaccording to the present disclosure;

FIG. 14 is a schematic diagram of a regenerative gas and vacuum controlsystem according to the present disclosure;

FIGS. 15A and 15B illustrate a flow chart of a method according to thepresent disclosure;

FIG. 16 is a plan, cross-sectional view of a batch reactor according tothe present disclosure;

FIG. 17 is a schematic diagram of a anaerobic digestion control systemaccording to the present disclosure;

FIG. 18A is a schematic diagram of the movement control system of FIG.17;

FIG. 18B is a schematic diagram of the directional control system ofFIG. 17;

FIG. 18C is a schematic diagram of the temperature control system ofFIG. 17;

FIG. 18D is a schematic diagram of the totalization and pressure sensingsystems of FIG. 17;

FIG. 19 is a schematic diagram of a chiller heat exchanger according tothe present disclosure;

FIG. 20A is a side, cross-sectional view of a biomaterial processingsystem according to the present disclosure; and

FIG. 20B is a plan, cross-sectional view of a biomaterial processingsystem according to the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings. In thefollowing description, well-known functions or constructions, such aspiping runs, valves, pumps, fans, and the like are not described indetail to avoid obscuring the present disclosure in unnecessary detail.Further, the process according to the present disclosure may optionallybe performed as a serial, continuous, or batch process, and combinationsthereof (e.g., sequential or continuous batch processing). The followingdescription and figures illustrate non-limiting embodiments of ananaerobic digestion system that may comprise any number of clarifiers,batch reactors, and digesters, among other aspects.

FIG. 1 illustrates an embodiment of an anaerobic digestion system 100 ofthe present disclosure. As shown in FIG. 1, the system 100 may includean influent collection tank 200, a clarifier 300, a batch reactor 400,and a digester 500. As shown in FIG. 1, in certain embodiments, theanaerobic digestion system 100 may also comprise one or more biologicalreactors 350 and 360, which may be used for testing purposes. As usedherein the term “clarifier” denotes any receptacle in which predigestionor pretreatment processing of at least one biomaterial may occur.Pretreatment processing may include homogenization, hydrolysis,including mechanical or acid treatment, pasteurization, and combinationsthereof. As used herein, the term “batch reactor” denotes any receptaclethat may also contain a digestion substrate (e.g., fixed and/orfluidized media) in which anaerobic digestion may occur. As used herein,the term “digester” denotes any receptacle in which anaerobic digestionmay occur. As used herein the term “biological reactor” denotes anyreceptacle in which materials for the predigestion processing of atleast one biomaterial, processes or partially processed digestate,and/or test samples of the foregoing may be housed for later use oranalysis. As used herein, the term “receptacle” denotes any containmentvessel system or systems including one or more chambers, containers,compartments, sections, tanks, vessels, reactors, housings, structures,and combinations thereof.

In some embodiments, the batch reactor 400 is a stand-alone anaerobicdigestion system that operates without the clarifier 300, the biologicalreactors 350, 360, or the digester 500. In these embodiments, digestatemay be fed to the batch reactor 400 from a digestate storage vessel (notshown) that stores preprocessed biomaterial. In other embodiments, theanaerobic digestion system includes the clarifier 300 and the batchreactor 400 and not the biological reactors 350, 360, or the digester500. In yet other embodiments, the clarifier 300 includes only tworeceptacles: a biomaterial receptacle and a digestate receptacle. Inthese embodiments, the receptacles may be positioned immediatelyadjacent to each other or positioned apart from each other, but fluidlycoupled to each other via a fluid line, such as a pipe. In still otherembodiments, the anaerobic digestion system includes the clarifier 300and the digester 500 and not the biological reactors 350, 360, or thebatch reactor 400.

FIGS. 2A and 2B show plan and cross-sectional views of an embodiment ofthe influent collection tank 200, respectively. The collection tank 200may be constructed of concrete and may include a floor, walls, and aceiling. The collection tank 200 includes an inlet 202 for supplying afirst biomaterial to be digested by the digestion system 100. The firstbiomaterial may include biomaterial that is generally in sludge orslurry form, and/or biomaterial having a nonzero chemical oxygen demand.In embodiments, the first biomaterial may include agricultural andindustrial waste. In further embodiments, the biomaterial may includefats-oils-greases (FOG), slaughterhouse waste, winery waste, municipalwaste, animal manures, domestic sludge waste, coffee waste water,chemical waste, and combinations thereof. In yet further embodiments,the first biomaterial may include any human or animal excrement, forexample, livestock manure produced by any domesticated animalsincluding, but not limited to, swine; horses; poultry, such as chickens,ducks, and geese; cattle, such as cows, steer, yaks, goats, and buffalo;and combinations thereof. The biomaterial may have a chemical oxygendemand (COD) per liter from about 1 gram to about 3,000 grams, inembodiments from about 10 grams to about 500 grams, in furtherembodiments from about 20 grams to about 100 grams. The biomaterial mayalso have volatile solids (VS) contents per liter from about 1 gram toabout 200 grams, in embodiments from about 10 grams to about 150 grams,in further embodiments from about 15 grams to about 60 grams.

The inlet 202 terminates within the collection tank 200 and directs theflow of the first biomaterial (e.g., influent) through a screen filter204. The screen filter 204 has a three-dimensional mesh structureconfigured to prevent any inorganic materials (e.g., rocks, catheters,needles, steel flooring particles, steel piping particles, plastics,mortalities, and the like) from entering the system 100. The collectiontank 200 also includes a pump 206, which may be a submersible pump thatis disposed at the bottom of the collection tank 200. The pump 206 isconfigured to remove the influent from the collection tank 202 andsupply the influent to the clarifier 300. The pump 206 is coupled topiping 250 for pumping out the influent stored in the collection tank200. The pump 206 may be operated automatically or manually (e.g., by auser).

The collection tank 200 may also include a float sensor 210, whichprovides fill level measurements to the system 100 including low andhigh fill level warnings. The low fill level warning may be used toprevent operation of the pump 206 and the high fill level may be used toprevent further addition of the influent into the collection tank 200.Automatic operation of the pump 206 may also be based on a variety ofsensor readings regarding the state of the system 100 as described infurther detail below, including but not limited to, the operationalstate (e.g., fill level) of the clarifier 300, the batch reactor 400,and the digester 500. The load of the pump 206 is also measured by oneor more sensors and is provided to the system 100. The load may becalculated by measuring the voltage and the current of the suppliedelectrical energy to determine input power.

In some embodiments, a single sensor is used to obtain multipledifferent data points. For example, the pressure transducer 225 shown inFIG. 2 generates pressure sensor data that may be used to determine boththe volume of the gas within the headspace of the influent collectiontank 200 and the volume of liquid biomaterial within the influentcollection tank 200.

The pressure sensor assembly 220 includes a pipe 224 that extends fromthe floor of the influent collection tank 200 to the headspace of theinfluent collection tank 200, where the pipe 224 bends at a right angleand couples to an aperture in a side wall of the influent collectiontank 200. The pressure sensor assembly 220 includes a first conduit 221having one end that is coupled to an air chamber on a first side of apressure sensing diaphragm within the pressure transducer 225. The otherend of the first conduit 221 is coupled to a first breather tube 227that passes through an aperture in the pipe 224 into the headspace ofthe influent collection tank 200. The pressure sensor assembly 220 alsoincludes a second conduit 222 having one end that is coupled to an airchamber on a second side of the pressure sensing diaphragm (opposite thefirst side). The other end of the second conduit 222 is coupled to asecond breather tube 228 that passes through the aperture in the sidewall of the influent collection tank 200 and is vented to atmosphere.

Before normal operation, the pressure sensor assembly 220 is calibratedby acquiring pressure sensor signals from the pressure transducer 225and determining the signal-to-noise ratio of the pressure sensor signalswhen the influent collection tank 200 is empty and when the influentcollection tank 200 is full. During normal operation, a logic controller802 (described below) acquires pressure sensor signals from the pressuretransducer 225 and determines the signal-to-noise ratio of the pressuresensor signals. The logic controller 802 then uses the signal-to-noiseratio information to determine both the volume of the gas and the volumeof the liquid within the influent collection tank 200. The pressuresensor assembly 220 may be disposed in other reactors of the digestionsystem 100 to obtain volume data.

The collection tank 200 is in fluid communication with the clarifier 300via piping 250. A flow meter 252 (in FIG. 1) is coupled to the piping250, which is adapted to measure the flow rate of the influenttherethrough. The flow rate measurement provides for a total volume ofthe influent. The system 100 may then determine the solid contents ofthe influent supplied to the clarifier 300 based on the flow rate andthe load of the pump 206.

With reference to FIG. 1, in embodiments, the clarifier 300 may includea first biomaterial (e.g., influent) intake receptacle 302, a secondbiomaterial (e.g., biomass) intake receptacle 304, and a digestatereceptacle 306. The clarifier 300 may be constructed as an in-ground,explosion-proof tank from concrete and/or other suitable materials. Theclarifier 300 may include a floor, walls, and a ceiling. The clarifier300 includes a wall 305 partitioning the clarifier into two portions,the receptacles 302, 304 and the receptacle 306, and a wall 303partitioning the receptacles 302 and 304. The receptacles 302, 304, and306 are in fluid communication with each other to allow for influent topass therebetween as described in further detail below. In embodiments,the receptacles 302, 304, 306 may be constructed as stand-alonestructures interconnected by piping. In further embodiments, theclarifier 300 may include a single receptacle for predigestionprocessing.

The receptacles 302 and 306 may have a reactor volume from about 1gallon to about 5,000,000 gallons, in embodiments, from about 1,000gallons to about 1,000,000 gallons, in further embodiments from about5,000 gallons to about 20,000 gallons. The receptacle 304 may have areactor volume from about 1 gallon to about 5,000,000 gallons, inembodiments, from about 1,000 gallons to about 1,000,000 gallons, infurther embodiments from about 5,000 gallons to about 10,000 gallons.

FIGS. 3A, 3B, and 3C show plan and cross-sectional views of anembodiment of the clarifier 300 taken along section lines 3B-3B and3C-3C, respectively. In embodiments, the piping 250 is coupled to thereceptacle 302 to provide for the flow of the influent. The receptacle302 operates as a raw influent slurry acceptance stage, and is used for,but is not limited to, pasteurization, solid particle size reduction,calibration of volatile solids and chemical oxygen demand, andcombinations thereof.

In embodiments, the second biomaterial, e.g., biomass, is also added tothe intake receptacle 304. As used herein, the term “biomass” denotesany organic material including, but not limited to, silage, such asfoliage, grasses, hay, straw, grains, legumes, and the like; compost;animal waste products, such as human waste and livestock manure having adesired amount of solids content. The amount of biomass added may bebased on the amount of solid contents of the influent in the receptacle302. Solid organic loading rate of the biomass may be from about 0.01grams of volatile solids per liter-day (g*VS/L*D⁻¹) to about 250g*VS/L*D⁻¹, in embodiments from about 0.05 g*VS/L*D⁻¹ to about 100g*VS/L*D⁻¹, in further embodiments from about 0.1 g*VS/L*D⁻¹ to about 5g*VS/L*D⁻¹.

In embodiments, the second biomaterial may include biomaterial that isin solid, semi-solid, or slurry form, and/or biomaterial that containsvolatile solids. The second biomaterial may include energy crops,post-harvest crops, post-consumer waste, non-hazardous laboratory waste,construction and demolition waste, post-consumer waste, animalby-products, food waste, residual waste, forestry waste, municipalsolids, and combinations thereof.

The receptacle 304 may include a recirculation chopper pump 314configured to chop the biomass thereby reducing the particle size of thebiomass. The pump 314 may be activated to circulate and process thebiomass as the biomass is subjected to various treatment processesdescribed below. The receptacle 304 operates an anaerobic hydraulicflush reactor (AHFR) as part of a two-stage process in series with thebatch reactor 400, which operates as a stationary bed anaerobic fixedfilm reactor (AFFR) as described in further detail below.

Once the receptacles 302 and 304 are loaded with the influent andbiomass, respectively, the influent and the biomass are pasteurized.Pasteurization of the influent and the biomass removes microorganismsfound therein, such as enteric species found in the digestive tract ofanimals. This provides for optimal inoculation of the influent and thebiomass with desired microorganisms suitable for anaerobic digestion asdescribed in further detail below.

The digestion system 100 includes a heat source 600, which may be anysuitable boiler, and multiple heat exchangers (e.g., the heat exchangers632 a-c, 634 a-b, 636 a-b, 608 a-d of FIG. 6) configured to heat thematerial being processed to a desired temperature. A variety ofdifferent heat exchanger configurations may be used, including, but notlimited to, a sleeve heater, in-line heater or a heater provided withinthe walls, floor, and/or ceiling of the clarifier 300, the batch reactor400, and the digester 500. The heating elements may be designed to heatspecific zones or regions of the system 100.

In some embodiments, the heat source 600 may be coupled to a steamgenerator (e.g., the steam generator 1727 of FIG. 17), which, in turn,may be coupled to one or more steam injectors that inject steam into theclarifier 300. A plurality of temperature sensors (e.g., the temperaturesensors 642 a-c, 644 a-b, 646 a-b, 648, 652 a-c, 654 a-b, 656 a-b, 658of FIG. 6) may be dispersed throughout the digestion system 100. Thelogic controller 802 may be coupled to the temperature sensors and heatexchangers to provide continuous, regulated heating of the clarifier300, the batch reactor 400, and the digester 500 by regulating theoutput of the heat source 600.

With reference to FIG. 4, the heat source 600 includes a plurality ofclosed-loop pipe runs configured to circulate a heating medium, such aswater, vapor, oil, and the like. The heat source 600 is coupled to heatexchange piping that is disposed within the clarifier 300. Inembodiments, the heat exchange piping may include a plurality of zones602 a, 602 b, 602 c disposed within the walls of the receptacles 302,304, 306, respectively. Each of the zones 602 a, 602 b, 602 c may beheated to a desired temperature to provide optimal conditions withineach of the receptacles 302, 304, 306.

Pasteurization may occur by heating the influent and the biomass withinthe receptacles 302 and 304, respectively, to a temperature from about40° C. to about 250° C., in embodiments from about 45° C. to about 100°C., and in further embodiments from about 50° C. to about 80° C. via thezones 602 a and 602 b for a time period from about 3 minutes to about 12hours, in embodiments from about 30 minutes to about 4 hours, in furtherembodiments from about 1 hour to about 3 hours until pasteurization isachieved. The dwell time and temperature may be varied to achieveoptimal pasteurization. After pasteurization, the receptacles 302 and304 may be maintained at a temperature from about 25° C. to about 50°C., in embodiments from about 30° C. to about 40° C., and in furtherembodiments from about 35° C. to about 38° C.

With reference to FIG. 1, in addition to the temperature within thereceptacles 302 and 304, the pH and oxidation reduction potential (ORP)of the contents thereof is also measured and maintained at a desiredlevel. The system 100 includes a chemical feed control assembly 700which is configured to measure and adjust pH and ORP of the materialbeing processed by the system 100. The system 100 may include aplurality of pH and ORP sensors and a plurality of chemical feed inletsdispersed throughout various components of the digestion system 100,e.g., the clarifier 300, the batch reactor 400, etc. The plurality ofchemical inlets are coupled to the chemical feed control assembly 700that is configured to introduce acidic or basic compounds to thesuspension of solid waste to control the pH and ORP.

With reference to FIG. 5, the chemical feed control assembly 700includes a plurality of probes 702, 704, 706 configured to measure pHand/or ORP of the contents stored within the clarifier 300 and the batchreactor 400. Each of the probes 702, 704, 706 includes a pH sensor 702a, 704 a, 706 a, an ORP sensor 702 b, 704 b, 706 b, and a control valve702 c, 704 c, 706 c. The chemical feed control assembly 700 alsoincludes a plurality of chemical supply tanks 720 a, 722 a, 724 a, 726 awhich store specific compounds suitable for adjusting pH and ORP of thematerial being processed by the system 100. Each of the chemical supplytanks 720 a, 722 a, 724 a, 726 a is coupled to a corresponding pump 720b, 722 b, 724 b, 726 b. The chemical feed control assembly 700 includesthe logic controller 802, which may be any suitable logical processingunit embodied as hardware, including but limited to, a processor, afield programmable gate array, a logic circuit, a programmable logiccontroller (PLC), and the like, or software, such as a virtualprocessing environment. The logic controller 802 is coupled to the pumps720 b, 722 b, 724 b, 726 b and the probes 702, 704, 706.

The chemical supply tanks 720 a, 722 a, 724 a, 726 a may include anysuitable strong mineral acid, including, but not limited to, sulfuricacid, nitric acid, hydrochloric acid, hydrofluoric acid, perchloricacid, and combinations thereof, and any suitable strong mineral base,including, but not limited to, sodium hydroxide, calcium carbonate,potassium hydroxide, calcium hydroxide, magnesium hydroxide, andcombinations thereof.

The logic controller 802 may also be coupled to a computerized controlinterface 712. In embodiments, the control interface 712 may includeterminal services, industrial control and data acquisition interfaces,and other industrial control systems. The control interface 712 providesfor local and/or remote (e.g., off site) user input and output. Thelogic controller 802 determines one or more suitable compounds to beadded to system 100 based on the measurements by the probes 702, 704,706. The logic controller 802 may interrogate the probes 702, 704, 706at regular intervals and/or when specifically requested by a user viathe control interface 712. In embodiments, the sampling may becontrolled using a proportional integral derivative (PID) control loopbased on a desired sampling rate, previously sampled pH and ORP values,set point pH and ORP values, and combinations thereof.

The logic controller 802 also calculates a desired rate of addition ofthe compounds to the system 100 to ensure that the compounds are addedin a controlled manner. In embodiments, the rate of addition may becalculated based on the circulation rate of the pumps (e.g., pump 314).Based on the measurement by the probes 702, 704, 706, the logiccontroller 802 signals corresponding pumps 720 b, 722 b, 724 b, 726 b torelease a desired amount of chemical feedstock at a desired rate. Thelogic controller 802 also controls operation of control valves 702 c,704 c, 706 c to allow for the flow of the chemical agents to a desiredlocation within the system 100.

With reference to FIGS. 1 and 5, once the biomass is pasteurized, the pHand ORP of the biomass within the receptacle 304 is measured. The probe702 is coupled to the pump 314, which provides a sample of the biomasswithin the receptacle 304 to the probe 702 for measuring pH and ORP ofthe biomass contained therein. The logic controller 802 signals the pump720 b to release a desired amount of chemicals from the tank 720 a at adesired rate based on the measured pH and ORP values. In embodiments,the tank 720 a may include, any strong mineral acid, including, but notlimited to, sulfuric acid, hydrochloric acid, and any of the otheracidic compounds described above including any combinations thereof. ThepH of the biomass is adjusted to a value of from 2 to about 6, inembodiments from about 3 to about 5 by the chemical feed controlassembly 700.

Once the pH is adjusted, hydrolysis of the biomass is commenced byintroducing hydrolytic microorganisms into the receptacle 302 from afirst biological reactor 350. The biological reactor 350 may have areactor volume from about 1 gallon to about 5,000,000 gallons, inembodiments, from about 1,000 gallons to about 1,000,000 gallons, infurther embodiments from about 5,000 gallons to about 10,000 gallons.The biological reactor 350 operates as a fermentation stage and a sourceof microorganisms, micronutrients, and inoculants for the processing ofbiomass within the receptacle 304. Hydrolytic microorganisms may bestored along with processed product, e.g., processed digestate, withinthe first biological reactor 350.

The biological reactor 350 is in fluid communication with the receptacle304 via piping 351. The biological reactor 350 includes a recirculationpump 352 that is used to transport the contents of the biologicalreactor 350 to the receptacle 304. The pump 352 may also be activatedperiodically to cycle between periods of circulation and stationarystorage.

With reference to FIG. 4, the biological reactor 350 also includes heatexchange piping 606 a coupled to the heat source 600. The piping 606 amay be disposed within or about the biological reactor 350 and isconfigured to maintain a desired temperature within the biologicalreactor 350 to provide optimum conditions for the hydrolytic (e.g.,liquid contents) microorganisms disposed therein. The biological reactor350 may be maintained at a temperature from about 10° C. to about 100°C., in embodiments from about 25° C. to about 50° C., in furtherembodiments from about 30° C. to about 40° C., in yet furtherembodiments from about 35° C. to about 38° C.

The first biological reactor 350 may include previously processeddigestate which is used as nourishment to maintain desired levels ofmicroorganisms within the biological reactor 350. In embodiments, thebiological reactor 350 may be refilled from outside sources to maintainrequired levels of microorganisms. Suitable hydrolytic microorganismsinclude, but are not limited to, Clostridium species, such as C.thermolacticum, C. thermohydrosulfuricum, C. thermosuccinogene, C.butyricum, C. pasteurianum, and C. beijirincki; Lactobacillus species,such as Lactobacillus paracasel; and Eubacteria species, such as E.aerogenes; and combinations thereof. The solids and hydraulic retentiontime within the biological reactor 350 may be from about 30 minutes toabout 40 days, in embodiments from about 1 hour to about 20 days, infurther embodiments from about 4 hours to about 10 days, in yet furtherembodiments from about 6 hours to about 12 hours.

With reference to FIG. 1, after the influent is pasteurized within thereceptacle 304, acidogenic microorganisms are introduced into thereceptacle 302 to commence acidogenesis of the influent. The biologicalreactor 360 may also have a reactor volume from about 1 gallon to about5,000,000 gallons, in embodiments, from about 1,000 gallons to about1,000,000 gallons, in further embodiments from about 5,000 gallons toabout 10,000 gallons. Similarly to the biological reactor 350, thebiological reactor 360 operates as a fermentation stage and a source ofmicroorganisms, micronutrients, and inoculants for the processing of theinfluent within the receptacle 302. The biological reactor 360 alsooperates as a quality control stage for inter-reactor transfers andeffluent discharge as described in further detail below. Acidogenicmicroorganisms may be stored along with processed product, e.g.,processed digestate, within the second biological reactor 360.

The biological reactor 360 is in fluid communication with the receptacle304 via piping 361. The biological reactor 360 includes a pump 362 thatis used to transport the contents of the biological reactor 360 to thereceptacle 304. The pump 362 may also be activated periodically to cyclebetween periods of recirculation and stationary storage.

With reference to FIG. 4, the biological reactor 360 also includes heatexchange piping 606 b coupled to the heat source 600. The piping 606 bmay be disposed within or about the biological reactor 360 and isconfigured to maintain a desired temperature within the biologicalreactor 360 to provide optimum conditions for the acidogenicmicroorganisms disposed therein. The biological reactor 360 may bemaintained at a temperature from about 10° C. to about 100° C., inembodiments from about 30° C. to about 80° C., in further embodimentsfrom about 35° C. to about 75° C., in yet further embodiments from about40° C. to about 60° C.

The biological reactor 360 also includes a pump 362, which may beactivated periodically to cycle between periods of circulation andstationary storage. The second biological reactor 350 may also includepreviously processed digestate. In embodiments, the biological reactor360 may be refilled from outside sources. Suitable acidogenicmicroorganisms include, but are not limited to, Syntrophobacter species,such as S. fumaroxidans, S. pfennigii, S. sulfatireducens, S. wolinii,and combinations thereof. The solids and hydraulic retention time withinthe biological reactor 360 may be from about 30 minutes to about 40days, in embodiments from about 1 hour to about 20 days, in furtherembodiments from about 4 hours to about 10 days, in yet furtherembodiments from about 6 hours to about 12 hours. The recycling of thedigestate is described in further detail below.

With reference to FIGS. 3A-3C, the receptacles 302 and 304 are in fluidcommunication therewith via first and second openings 308 and 310. Thefirst opening 308 is controlled by a flow control mechanism 312, such asa control valve or a hydraulically actuated sluice gate, and the secondopening 310 is in fluid communication with the recirculation chopperpump 314. The first opening 308 is disposed at a predetermined distancefrom the floor of the receptacle 304 to allow for separation of liquidand settled solid contents within the receptacle 304, thereby uncouplingsolids retention time and hydraulic retention time of the biomass withinthe receptacle 304. The distance may be at any level designed to retainthe solid contents of the biomass that settles to the floor of thereceptacle 304 therein while decanting (e.g., draining) the liquidcontents into the receptacle 302. Separation of liquid and solids may beaccomplished by actuating the flow control mechanism 312 (e.g., liftingthe sluice gate) and allowing the liquid contents of the biomass to flowinto the receptacle 302 until the liquid level drops below the opening308 or the flow control mechanism 312 is closed.

The solids and hydraulic retention time within the receptacle 302 may befrom about 3 minutes to about 48 hours, in embodiments from about 2hours to about 36 hours, in further embodiments from about 4 hours toabout 24 hours. The solids retention time within the receptacle 304 maybe from about 30 minutes to about 40 days, in embodiments from about 1hour to about 20 days, in further embodiments from about 4 hours toabout 10 days, in yet further embodiments from about 3 days to about 4days, and in still further embodiments from about 6 hours to about 12hours. The hydraulic retention time within the receptacle 304 may befrom about 1 hour to about 24 hours, in embodiments, from about 2 hoursto about 12 hours, in further embodiments from about 3 hours to about 8hours. During the retention period, the temperature, pH, and ORP valueswithin the receptacles 302 and 304 are maintained as described above.

Influent may be treated within the receptacle 302 for the duration ofthe retention periods described above and/or until a desired pH and/orORP level is achieved. Treated influent may have a pH from about 3 toabout 10, in embodiments from about 3.5 to about 9, in furtherembodiments from about 7 to about 8.5 and ORP from about −500 millivolts(mV) to about +50 mV, in embodiments about −400 mV to about 0 mV, infurther embodiments from about −200 mV to about −100 mV. Biomass may betreated within the receptacle 304 for the duration of the retentionperiods described above and/or until a desired pH and/or ORP level isachieved. The treated biomass may have a pH from about 3 to about 7, inembodiments from about 4 to about 6 and ORP from about −250 mV to about−50 mV, in embodiments about −100 mV to about −200 mV.

Once the influent and the biomass within the receptacles 302 and 304,respectively, has been sufficiently treated the contents of thereceptacles 302 and 304 are mixed. To mix the liquid and solid contentsof the receptacles 302 and 304, the flow control mechanism 312 is openedand the pump 314 is activated. The pump 314 chops the solid contents ofthe biomass thereby reducing the particle size thereof and pushes thecontents of the receptacle 304 into the receptacle 302 through theopening 310. Mechanical processing of the biomass, e.g., chopping,provides for an increased surface area of the material that may beprocessed by the microorganisms.

Hydrolytic microorganisms digest the biomass and the influent within theclarifier 300, which may include various proteins, fats, lignin,cellulosic species, and the like into corresponding monomers. Duringhydrolysis water content may be monitored and water may be added to theclarifier 300 to maintain hydrolysis. As a result of thedepolymerization of the biomass by the hydrolytic microorganisms, thegases, including, but not limited to, hydrogen sulfide, hydrogen,ammonia, and combinations thereof, are generated within the clarifier300. Acidogenic microorganisms breakdown the resulting monomers intovolatile organic acids, including, but not limited to, formic, acetic,propionic, lactic, butyric, and valeric acids, and the like; alcohols,such as methanol, ethanol, propanol, and the like; and gases, such ascarbon dioxide and combinations thereof are generated within theclarifier 300.

The circulation of the mixture of the biomass and the influent by thepump 314 also forces the contents of the receptacle 302 to pass throughthe opening 308 back into the receptacle 304. The recirculation of thecontents of the receptacles 302 and 304 mixes the pasteurized influentand hydrolyzed biomass. The mixing may continue for a period of timefrom about 1 minute to about 12 hours, in embodiments from about 1 hourto about 8 hours, in further embodiments from about 2 hours to about 4hours.

In embodiments, the microorganisms from the biological reactors 350 and360 may be added to the receptacles 302 and 304 after the mixing hascommenced. In further embodiments, the pH and ORP of the combinedcontents of the receptacles 302 and 304 may be measured by the probe 702as the pump 314 provides samples of the combined mixture to the probe702. The chemical feed control assembly 700 may then adjust the pH andthe ORP of the mixture during the mixing process based on themeasurements of the probe 702 as described above with respect to FIG. 5.

With reference to FIG. 1, once the biomass and the influent have beensufficiently mixed with the microorganisms from the biological reactors350 and 360, the mixture is transferred to the receptacle 306. Thereceptacle 306 operates as an equilibration and integration pointbetween the receptacles 302 and 304 and the downstream reactors (e.g.,batch reactor 400 and digester 500). With respect to FIG. 3A and FIG.3C, a second flow control mechanism 316, which may also be a flowcontrol valve or a hydraulically actuated sluice gate, provides accessbetween the receptacles 302 and 306. In embodiments, the receptacle 304or both of the receptacles 302 and 304 may be directly coupled to thereceptacle 306. The floor of the receptacle 302 may be sloped toward anopening 318 to provide for the flow of the contents from the receptacle302. Gravitational flow of the mixture allows for additional mixing ofthe pasteurized influent and hydrolyzed biomass. The clarifier 300 maybe configured so that the floor of the receptacle 306 is disposed at alower level than the floor of the receptacles 302 and 304 to achievevigorous mixing of the digestate when the digestate flows from the firstbiomaterial receptacle 302 to the digestate receptacle 306. It isunderstood that the material pumps described herein may be replaced withgravitational mechanisms for transporting or mixing digestate orbiomaterials.

The solids and hydraulic retention time of the digestate within thereceptacle 306 may be from about 1 hour to about 48 hours, about 3 hoursto about 36 hours, in further embodiments from about 4 hours to about 24hours and/or until a desired pH and/or ORP level is achieved. In someembodiments, the treated digestate may have a pH from about 4 to about9. In other embodiments, the treated digestate may have a pH from about5 to about 8. In other embodiments, the treated digestate may have a pHfrom about 6.5 to about 7.5. In some embodiments, the treated digestatemay have an ORP from about −300 mV to about −100 mV. In otherembodiments, the treated digestate may have an ORP from about −250 mV toabout −150 mV.

The digestate, which is a liquid suspension of solid matter, istransferred to the batch reactor 400 for further processing. Inembodiments, a portion of digestate is transferred to the batch reactor400, while a remaining portion may be transferred to the biologicalreactors 350 and 360 to provide nourishment for the hydrolytic andacidogenic organisms stored therein, respectively. Amount of thedigestate that may be transferred to the batch reactor 400 from theclarifier 300 may be from about 1% to about 100%, in embodiments fromabout 40% to about 90%, in further embodiments from about 50% to about75%. Amount of the digestate that may be transferred to the biologicalreactors 350 and 360 from the clarifier 300 may be from about 0.5% toabout 25%, in embodiments from about 1% to about 20%, in furtherembodiments from about 5% to about 15%.

As shown in FIG. 1, the biological reactor 350 is in fluid communicationwith the receptacle 306 via piping 353 a, which is coupled to the piping353 b and 353 c. Piping 353 c interconnects the biological reactor 350and the digester 500, and the piping 353 b interconnects the biologicalreactor 350 and the receptacle 306 of the clarifier 300. The biologicalreactor 360 is also in fluid communication with the receptacle 306 viapiping 320 a, 320 b, and 320 c. A flow meter 322 is coupled to theportion 320 b, which is adapted to measure the flow rate of thedigestate therethrough. To avoid unnecessary detail, various piping runsand control valves interconnecting the components (e.g., clarifier 300,batch reactor 400, biological reactors 350 and 360, digester 500, etc.)of the system 100 are omitted. It would be readily apparent to a personof ordinary skill in the art the type and the location of the controlvalves that may be used to achieve desired flow control through thesystem 100.

The biological reactor 360 may be used as a temporary storage for thedigestate prior to transferring of the digestate to subsequent treatmentstages. The biological reactor 360 may also be used to increaseretention time for the microorganisms to hydrolyze the digestate. Inembodiments, the biological reactor 360 may also be used to determinewhether the digestate has been sufficiently hydrolyzed. If it isdetermined that additional hydrolysis is required, the digestate may betransferred back to the clarifier 300 via piping 361 which interconnectsthe biological reactor 360 and the receptacle 302 as shown in FIGS. 1,3A and 3B. The digestate may then be combined with additional hydrolyzedbiomass from the receptacle 304 and moved to the receptacle 306 aftermixing as described above with respect to FIGS. 3A-3C. In furtherembodiments, the biological reactors 350 and 360 may be interconnectedvia piping (not shown) to provide for addition of microorganismsdirectly into the biological reactor 360. As shown in FIG. 1, thedigestate from the clarifier 300 is fed to the batch reactor 400 throughthe piping 320 a, 320 b, 320 d. In some embodiments, solids andinoculums from the digestate receptacle 306 of the clarifier 300 may bestep fed to the batch reactor 400.

FIGS. 6A, 6B, and 6C show plan and cross-sectional views of the batchreactor 400 taken through lines 6B-6B and 6C-6C, respectively. The batchreactor 400 may be constructed of concrete and may include a floor,walls, and a ceiling. With reference to FIG. 1, an embodiment of thebatch reactor 400 is shown as a multi-chamber reactor providing aserpentine flow path for the digestate supplied thereto as representedby arrows 430 in FIG. 7. In particular, the batch reactor 400 mayinclude a plurality of longitudinal flow chambers 402, 406, 408, 410,412 arranged in a serpentine configuration and separated by partitionwalls 403, 405, 407, 411, respectively. In embodiments, the chambers402, 406, 408, 410, 412 may be arranged in any configuration providingfor fluid communication between the chambers 402, 406, 408, 410, 412. Inembodiments, the chambers 402, 406, 408, 410, 412 may be arranged in alinear configuration (e.g., serially interconnecting the flow chambers402, 406, 408, 410, 412).

The batch reactor 400 also includes drainage chambers 404, 414 forcollecting settled solids and recirculating unprocessed digestate. Thedrainage chamber 404 is in direct fluid communication with the chambers402, 406, such that the digestate flows from the chamber 402 through thechamber 404 and into the chamber 406. The drainage chamber 414 is indirect fluid communication with the chambers 408 and 412, which areseparated by third and fourth flow control mechanisms 416 and 418,respectively. The flow chambers 408 and 410 are also separated by a flowcontrol mechanism 420. Similarly to the first and second flow controlmechanisms 312, 316, the flow control mechanisms 416, 418, 420 may alsobe flow control valves or hydraulically actuated sluice gates. The flowcontrol mechanism 420 separates the chambers 402, 406, 408 into a firstportion 413 and the chambers 410 and 412 into a second portion 415.

The batch reactor 400 may have a reactor volume from about 1 gallon toabout 5,000,000 gallons, in embodiments, from about 1,000 gallons toabout 1,000,000 gallons, in further embodiments from about 5,000 gallonsto about 20,000 gallons. The first portion 413 may have a reactor volumefrom about 10% to about 90% of the total volume of the batch reactor400, in embodiments from about 25% to about 75% of the total volume ofthe batch reactor 400. The second portion 415 may have a reactor volumefrom about 10% to about 90% of the total volume of the batch reactor400, in embodiments from about 25% to about 75% of the total volume ofthe batch reactor 400.

The solids retention time within the first portion 413 of the batchreactor 400 may be from about 30 minutes to about 40 days, inembodiments from about 1 hour to about 20 days, in further embodimentsfrom about 4 hours to about 10 days, in yet further embodiments fromabout 3 days to about 6 days, and in still further embodiments fromabout 6 hours to about 12 hours. The hydraulic retention time within thefirst portion 413 of the batch reactor 400 may be from about 1 hour toabout 48 hours, in embodiments from about 2 hours to about 36 hours, infurther embodiments from about 3 hours to about 8 hours.

The solids retention time within the second portion 415 of the batchreactor 400 may be from about 30 minutes to about 40 days, inembodiments from about 1 hour to about 20 days, in further embodimentsfrom about 4 hours to about 10 days, in yet further embodiments fromabout 3 days to about 6 days, and in still further embodiments fromabout 6 hours to about 12 hours. The hydraulic retention time within thesecond portion 415 of the batch reactor 400 may be from about 1 hour toabout 48 hours, in embodiments from about 2 hours to about 36 hours, infurther embodiments from about 3 hours to about 24 hours, in yet furtherembodiments from about 4 hours to about 8 hours.

The floor of the chambers 402, 406, 408, 410, 412 may be sloped downwardin the direction indicated by the arrows 430 to provide forgravitational flow of the digestate through the batch reactor 400. Inaddition, circulation of the digestate through the batch reactor 400 isalso accomplished by circulation pumps 450 and 460 which are coupled viapiping 452 a and 462 a to the drainage chambers 404 and 414,respectively. The pump 450 is also coupled to the digester 500 viapiping 452 b and provides processed digestate thereto. The pump 460 iscoupled to the piping 462 b which feeds back into the flow chamber 402to provide for recirculation of the digestate through the batch reactor400. The pump 460 is also coupled to the piping 462 c allowing thewithdrawal of solid effluent for disposal. As shown in FIG. 8, each offlow chambers 402, 406, 408, 410, 412 is filled with a digestionsubstrate 440 on which a consortium of suitable microorganisms aredisposed. The digestion substrate 440 may be any suitable substrateincluding media that may be formed from any suitable material,including, but not limited to, plastics, ceramics, glass, orcombinations thereof. The digestion substrate 440 may include particlesof any suitable shape, including, but not limited to, toroidal,polygonal, granular, spherical, cylindrical, and combinations thereofhaving a diameter, cross-sectional width or height of from about 1micron to about 30 centimeters, in embodiments from about 10 microns toabout 1 centimeter. The particles may be solid, porous or combinationsthereof. The digestion substrate 440 may have a surface area of fromabout 5 square feet (sq. ft.) per cubic foot to about 5,000 sq. ft/cu.ft., in embodiments from about 30 sq. ft/cu. ft. to about 1,000 sq.ft/cu. ft. The digestion substrate 440 may be loaded with acetogenicmicroorganisms. Suitable acetogenic microorganisms include, but are notlimited to, Clostridium species, such as C. acetobutylicum, C.perfringens, C. novyi, C. septicum, C. aciditolerans, C. frigidicarnis,C. acetireducens, and combinations thereof. In embodiments, digestionsubstrate 440 may be loaded with any suitable microorganisms includingbut not limited to: hydrolytic, saccharolytic, proteolytic, lipolytic,nitrate reducers, nitrite reducers, iron reducers, manganese reducers,sulfate reducers, acidogenic, acetogenic, methanogenic, organic acidfermenters, alcohol fermenters, and combinations thereof.

As the digestate flows through the batch reactor 400, the digestatecomes in contact with the film media 440. The acetogenic microorganismsbreakdown the volatile organic acids and alcohols found in the digestateinto constituent volatile organic acids, such as formic and acetic acidsusing the water found in the digestate. Water may be continuouslysupplied to the batch reactor 400 to maintain the acetogenesis.Acetogenesis also generates hydrogen and carbon dioxide gases. Inembodiments, the digestion substrate 440 may be loaded with any type ofmicroorganisms suitable for digestion of organic matter allowing thebatch reactor 400 to run the entire digestion process as described infurther detail below.

With reference to FIGS. 4, 6A, and 9, the batch reactor 400 alsoincludes heat exchange piping, namely, first and second zones 604 a and604 b, coupled to the heat source 600. The zones 604 a and 604 b may bedisposed within or about the batch reactor 400 and are configured tomaintain a desired temperature within the first and second portions 413and 415 of the batch reactor 400 to provide optimum conditions for themicroorganisms disposed therein.

Each of the zones 604 a, 604 b includes circulation loops 402 a, 406 a,408 a, 410 a, 412 a, and 402 b, 406 b, 408 b, 410 b, 412 b disposedwithin the flow chambers 402, 406, 408, 410, 412, respectively. Each ofthe zones 604 a, 604 b may be heated to a desired temperature. Inembodiments, the zone 604 a may be heated to a first temperature whereasthe zone 604 b may be heated to a second temperature, which may be thesame as or different from the first temperature. The first temperaturemay be suitable for mesophilic microorganisms and may be from about 25°C. to about 40° C., in embodiments from about 35° C. to about 38° C. Thesecond temperature may be suitable for thermophilic microorganisms andmay be from about 45° C. to about 100° C., in embodiments from about 50°C. to about 60° C.

Each of the circulation loops 402 a, 406 a, 408 a, 410 a, 412 a, and 402b, 406 b, 408 b, 410 b, 412 b may be selectively isolated via isolationvalves (not shown) to maintain each of the flow chambers 402, 406, 408,410, 412 at a desired temperature. In embodiments, circulation loops 402a, 406 a, 408 a of the first zone 604 a and 410 b, 412 b of the secondzone 604 b may be activated such that the flow chambers 402, 406, 408are heated to the first temperature and the flow chambers 410 and 412are heated to the second temperature. This configuration tailors thetemperature to each of the flow chambers 402, 406, 408, 410, 412 toprovide optimum conditions for the microorganisms disposed therein.

The digestate from the clarifier 300 enters the batch reactor 400 intothe flow chamber 402. As the digestate is pumped through the piping 320d, the pH and ORP of the digestate is sampled by the probe 704, which iscoupled thereto as shown in FIG. 5. The pH and ORP of the digestatewithin the first portion 413 of the batch reactor 400, which includesthe chambers 402, 406, 408, is adjusted by the chemical feed controlassembly 700. The pH may be adjusted to a value of from about 3 to about10, in embodiments from about 5 to about 9, in further embodiments fromabout 6 to about 6.5 and the ORP may be adjusted to a value of fromabout −500 mV to about +50 mV, in embodiments from about −400 mV toabout 0 mV, in further embodiments from about −250 mV to about −150 mV.The logic controller 802 signals the pump 722 b to release a desiredamount of chemicals from the tank 722 a at a desired rate based on themeasured pH and ORP values.

The chemical feed control assembly 700 also measures the pH and ORP ofthe digestate as it passes through the chambers 410 and 412 using theprobe 706. The pH and ORP of the digestate within a second portion 415of batch reactor 400, which includes the chambers 410 and 412, is alsoadjusted by the chemical feed control assembly 700. The pH may beadjusted to a value of from about 3 to about 10, in embodiments fromabout 5 to about 9, in further embodiments from about 6.5 to about 7 andthe ORP may be adjusted to a value of from about −500 mV to about +50mV, in embodiments from about −400 mV to about 0 mV, in furtherembodiments from about −250 mV to about −150 mV. The logic controller802 signals the pumps 724 b and 726 b to release a desired amount ofchemicals from the tanks 724 a and 726 a, respectively, at a desiredrate based on the measured pH and ORP values.

In embodiments, the chemicals stored within the tank 722 a that are fedinto the flow chambers 402, 406, 408 may be different from the chemicalsstored within the tanks 724 a and 726 a that are fed into the flowchambers 410 and 412 to tailor the pH and ORP within these chambers 402,406, 408, 410, 412. This configuration in combination with the first andsecond zones 604 a, 604 b allows the system 100 to tailor thetemperature as well as pH and ORP within the flow chambers 402, 406,408, 410, 412 to obtain suitable growth conditions for variousmicroorganisms.

A chelating agent may be added to the digestate to remove or coagulatemetals found therein. Influent collected from the livestock and farmanimals may contain undesirable levels of metals typically found in thefeed. Metals may include, but are not limited to, iron, lead, aluminum,silver, nickel, and ions, micro and nanoparticles, molecules, andcombinations thereof. In embodiments, suitable chelating agents include,for example, aluminum sulfate, hydrated potassium aluminum sulfate(alum), organic acids such as ethylene diamine tetra acetic acid (EDTA),GLDA (commercially available L-glutamic acid N,N diacetic acid), humicand fulvic acids, peta-acetic and tetra-acetic acids; salts of organicacids including salts of methylglycine diacetic acid (MGDA), and saltsof ethylenediamine disuccinic acid (EDDS); esters of organic acidsincluding sodium gluconate, magnesium gluconate, potassium gluconate,potassium and sodium citrate, nitrotriacetate (NTA) salt; substitutedpyranones including maltol and ethyl-maltol; water soluble polymersincluding polyelectrolytes that contain both carboxylic acid (COOH) andhydroxyl (OH) functionalities; and combinations thereof. In embodiments,EDTA, a salt of methylglycine diacetic acid (MGDA), or a salt ofethylenediamine disuccinic acid (EDDS), may be utilized as a chelatingagent. The chelating agent may be added in an amount from about 0.001%to about 1% by weight of the digestate, in embodiments from about 0.01%to about 0.05%, in further embodiments from about 0.015% to about 0.02%.The chelating agent complexes or chelates with the coagulant metals,thereby extracting the metals from the digestate.

The resulting metal complexes settle to the bottom of the batch reactor400, namely, the drainage chamber 404, from where the complexes areremoved by the pump 450 into the digester 500 where they settle to thebottom thereof. The floor of the drainage chamber 404 is at a lowerlevel than the floor of the flow chambers 402 and 406, allowing theheavier metal complex particles to sink to the bottom for subsequentremoval.

The flow of the digestate through the batch reactor 400 may also becontrolled by actuating the flow control mechanisms 416, 418, 420 in anydesired sequence and/or for any desired duration. In embodiments, theflow control mechanisms 416 and 418 may remain closed to increasedigestate dwell time within the batch reactor 400. During that time, theflow control mechanism 420 may be closed to ensure that the digestatestays only within the first portion 413 (e.g., mesophilic reactormaintained at the first temperature). The digestate may be treatedwithin the first portion 413 for a period of time from about 30 minutesto about 40 days, in embodiments from about 4 hours to about 10 daysand/or until a desired pH and/or ORP level is achieved. Treateddigestate may have a pH from about 3 to about 10, in embodiments fromabout 5 to about 9, in further embodiments from about 6 to about 7 andan ORP from about −500 mV to about +50 mV, in embodiments about −400 mVto about 0 mV, in further embodiments from about −150 mV to about −250mV.

As described above, the pH, ORP and temperature may be individuallycontrolled for each specific chamber 402, 406, 408, 410, 412.Controlling the flow of the digestate via flow control mechanisms 416,418, 420 allows for control of the length of time that the digestate isexposed to the varying conditions within the batch reactor 400. Infurther embodiments, the flow control mechanism 420 may be opened toallow the digestate to flow into the second portion 415 (e.g.,thermophilic reactor maintained at the second temperature). The chambers410 and 412 may be at a different pH, ORP and temperature than the firstportion 413. The flow control mechanisms 416 and 418 may be opened toallow the digestate to be recirculated by the pump 460 through thepiping 462 b. The digestate may be treated within the second portion 415for a period of time from about 30 minutes to about 40 days, inembodiments from about 4 hours to about 10 days and/or until a desiredpH and/or ORP level is achieved. Treated digestate may have a pH fromabout 3 to about 10, in embodiments from about 5 to about 9, in furtherembodiments from about 6 to about 7 and ORP from about −500 mV to about+50 mV, in embodiments about −400 mV to about 0 mV, in furtherembodiments from about −150 mV to about −250 mV.

The digestate may be continuously pumped off via the pump 450 from thedrainage chamber 404 into the digester 500 for further processing. Inembodiments, the pumps 450 and 460 may be operated in tandem to providefor continual recirculation and removal of the digestate or in sequence,to ensure that removal of the digestate occurs only after the digestatehas undergone acetogenesis to a desired degree.

In some embodiments, the batch reactor 400 may be a stand-alonedigestion system that receives digestate from a digestate source otherthan the clarifier 300 and continuously recirculates the digestate untilthe digestion process is complete. When a digestion cycle is complete,all or a portion of the processed digestate may be wasted as effluent.The digestate source may include a storage receptacle containingdigestate or a mixing receptacle in which digestate solids are mixedwith a liquid.

As shown in FIGS. 10, 11, and 12, the digester 500 may be a leach bedreactor configured to operate as a modified mix, settle, and decantsystem. The digester 500 may have a reactor volume from about 1 gallonto about 5,000,000 gallons, in embodiments, from about 1,000 gallons toabout 4,000,000 gallons, in further embodiments from about 500,000gallons to about 1,000,000 gallons. The digester 500 may be constructedas an in-ground pit with concrete floor and walls or any other suitablematerial. The surface of the digester 500 may be lined with any suitablematerial, including, but not limited to, high-density polyethylene,glass, polytetrafluoroethylene, and the like. The hydraulic retentiontime within the digester 500 may be from about 1 day to about 60 days,in embodiments from about 10 days to about 50 days, in furtherembodiments from about 20 days to about 30 days. The solid retentiontime within the digester 500 may be from about 1 day to about 90 days,in embodiments from about 20 days to about 90 days, in furtherembodiments from about 30 days to about 40 days.

The piping 452 b from the batch reactor 400 is connected to a flexibleinlet 502 as shown in FIGS. 10 and 11. The inlet 502 includes a flexibleportion 504 coupled to the piping 452 b at one end and to a rigid outletportion 506 at the other end. In embodiments, the rigid portion 506 maybe Y-shaped with respect to the flexible portion 504 having a firstsegment 506 a and a second segment 506 b. The angle between the firstand second segments 506 a and 506 b, a, may be less than the anglebetween each of the first and second segments 506 a and 506 b and theflexible portion 504, b and c, respectively. The first and secondsegments 506 a and 506 b may be of same or different lengths as shown inFIG. 10. The angular configuration and the Y-shape of the portion 506project the digestate stream in two different directions. The streaminggenerates vortices, which mix the contents of the digester 500. Theflexible portion 504 may be formed from any suitable material that wouldallow the inlet 502 to float up along with the contents of the digester500 at least partially on the surface thereof as it is continuouslyfilled. Suitable materials include, but are not limited to,semi-crystalline thermoplastics, amorphous thermoplastics, andcombinations thereof. The digestate within the digester 500 may have aratio of liquid to solid contents from about 0.1% to about 25%, inembodiments from about 5% to about 20%, in further embodiments fromabout 10% to about 15%.

With respect to FIGS. 4, 11 and 12, the digester 500 also includes heatexchange piping 608 disposed within, in embodiments at the bottom of thedigester 500 as shown in FIG. 11 or about the digester 500. The heatexchange piping 608 is configured to maintain the temperature within thedigester 500 to provide optimum conditions for the microorganismsdisposed therein from about 25° C. to about 60° C., in embodiments fromabout 30° C. to about 40° C., in further embodiments from about 35° C.to about 38° C. The heat exchange piping 608 may include one or morecirculation loops 608 a, 608 b, 608 c, 608 d, which may be disposed in aserpentine fashion throughout the digester 500 to maximize the surfacearea of the heat exchange piping 608.

The digester 500 includes methanogenic microorganisms. Suitablemethanogenic microorganisms include, but are not limited to,Methanothermobacter species, Methanobacterium oinelianskii, Mb.formicium, Mb. sohngenii, Methanosarcina barkeri, Ms. Methanica, Mc.mazei, Methanobacteriaceae, Methanosarcinaceae, Methanosaetaceae,Methanocorpusculaceae, Methanomicrobiaceae, and combinations thereof.The methanogenic microorganisms breakdown the volatile organic acids andalcohols found in the digestate into methane, hydrogen, and carbondioxide gases. In addition, various gases, including, but not limitedto, carbon dioxide and hydrogen, are reacted to form methane and water.

The digester 500 is also coupled via the piping 353 d to a digester pumpstation 550 having a pump 555, which is configured to remove and/orrecirculate the digestate contained within the digester 500. Thedigester pump station 550 is coupled to the piping 353 c which isconnected to the biological reactor 350 via the piping 353 a and thereceptacle 306 via the piping 353 b. The digester pump station 550removes the digestate from the digester 500 and recirculates it throughthe biological reactor 350 and/or the receptacle 306. The pump 322supplies the digestate back to the digester 500 through the piping 323e. Recirculated digestate from the digester 500 may be further processedand/or mixed with unprocessed biomass and influent within the clarifier300 and processed within the batch reactor 400 as described above priorto being added back into the digester 500.

With respect to FIGS. 13 and 14, the system 100 also includes a gas andmass flow control assembly 800. The flow control assembly 800 isconfigured to sample gases generated within the clarifier 300, thebiological reactors 350 and 360, the batch reactor 400, and the digester500. The gas and mass flow control assembly 800 is also configured toprovide the measurements to a logic controller 802, which then outputsthe data to a user and/or automatically controls the flow of thedigestate and/or gases through the system 100. The logic controller 812may also be coupled to the computerized control interface 712, which isdescribed above with respect to FIG. 5. The logic controller 802 may beany suitable logical processing unit embodied as hardware, including butlimited to, a processor, a field programmable gate array, and the likeor software, such as a virtual processing environment.

FIG. 13 illustrates a gas and mass flow control assembly 800 thatcontrols flow of gases from the digester 500, the clarifiers, and thereactors to the digester 500 or the gas take off 830. As shown in FIG.13, the logic controller 802 is coupled to a plurality of flow meters823-829, a plurality of pressure sensors 843-849, and a plurality of gasflow control valves 853-859, which are in fluid communication with thedigester 500, the receptacles 304 and 302 of the clarifier 300, thebiological reactors 350 and 360, and the first and second portions 413and 415 of the batch reactor 400, respectively. In some embodiments, theplurality of pressure sensors 843-849 may be replaced with a singlepressure sensor 841 that is fluidly coupled to the output of the valveassembly 817. In this configuration, the logic controller 802 operatesthe valve system 817 to selectively couple each of the sample ports833-839 to the pressure sensor 841 so that the pressure sensor 841 canmeasure the pressure within the digester 500, the receptacles 304 and302 of the clarifier 300, the biological reactors 350 and 360, and thefirst and second portions 413 and 415 of the batch reactor 400.

The gas and mass flow control assembly 800 also includes a gas flowcontrol valve 852 that is fluidly coupled between the gas take off 830and the digester 500, the receptacles 304 and 302 of the clarifier 300,the biological reactors 350 and 360, and the first and second portions413 and 415 of the batch reactor 400. The logic controller 802 controlsthe actuation of the gas flow control valves 852-859 based on the datagenerated by the gas flow meters 823-829 and the pressure sensors843-849. In this configuration, the logic controller 802 controls theflow of gases between any of the receptacles 304, 302 of the clarifier300 or reactors 350, 360, 400 and the digester 500 or the gas take off830.

The digester 500, the receptacles 304 and 302 of the clarifier 300, thebiological reactors 350 and 360, and the first and second portions 413and 415 of the batch reactor 400 are also in fluid communication withgas sample ports 833-839, respectively. The gas sample ports 833-839 areconfigured to provide a desired amount of gas to the gas analyzer 820.The gas pressure sensors 843-849 provide continual gas pressure readingswithin the digester 500, the receptacles 304 and 302 of the clarifier300, the biological reactors 350 and 360, and the first and secondportions 413 and 415 of the batch reactor 400.

Each of the sample ports 833-839 is fluidly coupled to a valve system817, which controls the flow of gas samples to a sample conditioner 818.The valve system 817 is configured to allow only a single gas sample topass to the sample conditioner 818 to prevent mixing of the gas samples.The sample conditioner 818 prepares the gas samples prior to passing thegas samples to a gas analyzer (e.g., a chromatograph 820), whichanalyzes the gas samples and provides the concentration of constituentgases of each of the gas samples to the logic controller 802. Thechromatograph 820 is also coupled to the control interface 712 viachromatography software 822 that may output gas analysis results to theuser.

The gas pressure and concentration values as determined by the mass flowcontrol assembly 800 may be used in conjunction with the pH and ORPvalues as determined by the chemical control assembly 700 to determinewhen the digestate may be transported between the clarifier 300, thebatch reactor 400, the biological reactors 350 and 360, and the digester500. The chemical and flow controllers 700 and 800 may be coupleddirectly to any of the flow control mechanisms, valves, pumps, fans, andother components described in the present disclosure to allow for remoteoperation thereof. In embodiments, the pH, ORP, gas pressure, andconcentration may be outputted via control interface 712 allowing formanual control over the system 100. In further embodiments, the system100 may be automated, such that the chemical and flow control assembly700 and 800 automatically operate the components of the system 100 toprovide for automatic transport of the digestate between the clarifier300, the batch reactor 400, the biological reactors 350 and 360, and thedigester 500.

The logic controller 802 also controls the flow of gaseous byproductsfrom the digestion processes between the clarifier 300, the batchreactor 400, the biological reactors 350 and 360, and the digester 500.This is accomplished by actuating the valves 853-859. The logiccontroller 802 may operate the valves of each of the gas samplers804-816 at regular intervals, based on automatic commands from the logiccontroller 802, user requests via the control interface 712, andcombinations thereof. In embodiments, the valves 853-859 may becontrolled using PID control loops 803-809, respectively, based on adesired sampling rate, gas pressure measured by the pressure sensors843-849, gas concentrations determined by the chromatograph 820 andchromatography software 822, gas pressure setpoint values, and gasconcentration setpoint values.

The valves 852-859 are opened to collect gaseous byproducts generatedduring digestion within the clarifier 300, the biological reactors 350and 360, the batch reactor 400, and the digester 500. The gas flowmeters 823-829 provide the gas flow measurements to the logic controller802 allowing for the determination of when a desired amount of gas hasbeen withdrawn. The withdrawn gas may be either transported to theclarifier 300, the batch reactor 400, the biological reactors 350 and360, the digester 500, or gas take-off 830 as described in furtherdetail below.

The logic controller 802 may actuate the valves 852-859 concurrently toallow for the flow of the gases between the receptacles 302 and 304 ofthe clarifier 300, the biological reactors 350 and 360, and the firstand second portions 413 and 415 of the batch reactor 400, and thedigester 500. As shown in FIG. 14, the logic controller 802 is alsocoupled to a second plurality of gas sample ports 871-874.

FIG. 14 illustrates a regenerative gas and vacuum control system thatmay be used together with the gas and mass flow control assembly of FIG.13. The valve system 817 is in fluid communication with the sample ports833-839 of the digester, clarifiers, and batch reactors. The valvesystem 817 is configured to selectively withdraw a desired amount of gasfrom the sample ports 871-874 of the digester 500, clarifier 300, andreactors 350, 360, 400 and provide the sampled gas to the gas analyzer820 (e.g., a chromatograph). The gas sample ports 871-874 are used insubstantially the same manner as the gas sample ports 833-839 of FIG.13, namely, the gas sample ports 871-874 provide gas samples to the gasanalyzer 820. The logic controller 802 operates the gas flow controlvalves 891-894 based on the gas pressure measured by the pressuresensors 881-884, the gas flow measured by the gas flow meters 861-864,and the concentration values determined by the gas analyzer 820. The PIDcontrol loops 811-814 monitor and control gas flow through gas piping840, which interconnects the clarifier 300, the biological reactors 350and 360, the batch reactor 400, and the digester 500.

Transportation of gases between the clarifier 300, the biologicalreactors 350 and 360, the batch reactor 400, and the digester 500 allowsfor removing gases that are generated in one portion of the system 100to another portion of the system 100 where such gases are used asreactants. In embodiments, the clarifier 300 and the batch reactor 400generate hydrogen gas during hydrolysis, acidogenesis, and acetogenesisreactions that occur therein and the hydrogen gas is used duringmethanogenesis process within the digester 500 as described above. Thus,supplying the hydrogen gas to the digester 500 from the clarifier 300and the batch reactor 400 provides for more efficient utilization of thereaction byproducts.

With reference to FIGS. 11, 12, and 14, a gas diffuser 610 is disposedat the bottom of the digester 500. The gas diffuser 610 is coupled tothe gas piping 840 and includes a plurality of branches 610 a, 610 b,610 c, 610 d. The gas diffuser 610 also includes a plurality of gasdiffusers 611 coupled to the branches 610 a, 610 b, 610 c, 610 d. Thegas diffusers 611 may be constructed as a longitudinal, substantiallycylindrical pipe termination with a plurality of openings of varying orsimilar diameter. The gas collected by the flow control assembly 800 ispassed through the piping 840 and into the gas diffuser 610 from whichthe gas is bubbled through the contents of the digester 500. Thediffused gas agitates the digestate of the digester 500 as it isdiffused therethrough. As described above, the gas is also used in themethanogenesis occurring within the digester 500. Any remaining gasexits the digestate and is collected by a stretchable cover 514 disposedover the digester 500 as shown in FIG. 11.

The cover 514 may be formed from any elastic material that may beinflated under the pressure from the gases generated by the digester500. The gases may be withdrawn from the volume enclosed by the cover514 to the gas take-off 830, a flare burners 850, an emergency vent 860,and combinations thereof. The flare burners 850 and the emergency vent860 are coupled to the pressure sensors 884 and 885, respectively, whichprovide gas pressure measurements to the logic controller 802. The logiccontroller 802 uses these gas pressure measurements to control gas flowfrom the digester 500 to the emergency evacuation vent 860 and/or theflare burners 850. The flare burners 850 and the emergency vent 860 areused to relieve the gas pressure within the digester 500 if aninsufficient amount of gas is being removed by the gas take-off 830.

The gas take-off 830 is coupled to the piping 840 and removes the gasfrom the clarifier 300, the biological reactors 350 and 360, the batchreactor 400, and the digester 500 for processing, for transport, or forfurther use at the heat source 600 or other heat and/or powergenerators. The gas take-off 830 is coupled to one or more scrubbers 832that remove undesirable gases, including, but not limited to, hydrogensulfide, ammonia, carbon dioxide, and combinations thereof, prior totransporting purified methane to the heat source 600. The heat source600 utilizes the methane extracted from the system 100 to maintain thetemperature within the clarifier 300, the biological reactors 350 and360, the batch reactor 400, and the digester 500 as described above.Additional methane may be utilized by other types of generators togenerate electricity and the like.

FIGS. 15A and 15B illustrate a method of the present disclosure. Themethod includes loading the influent and the biomass into thereceptacles 302 and 304 of the clarifier in steps 1010 and 1020,respectively. The influent and the biomass are then pasteurized in steps1030 and 1040. After pasteurization and balancing pH and ORP valueswithin the clarifier 300, acidogenic and hydrolytic microorganisms areadded to the clarifier 300 from the biological reactors 350 and 360 insteps 1050 and 1060, respectively. In step 1070, the contents of thereceptacles 302 and 304, namely, the influent and the biomass, are mixedto form a digestate and are transferred to the receptacle 306. In step1080, the digestate from the clarifier 300 is transferred to the batchreactor 400. In step 1090, the temperature within each of the first andsecond portions 413 and 415 of the batch reactor 400 is regulated to adesired level. In step 1100, the digestate is passed through thedigestion substrate 440 disposed within multiple flow chambers 402, 406,408, 410, 412 of the batch reactor 400. In step 1110, a chelating agentmay be added to remove metals from the digestate before furtherprocessing. After passing through the batch reactor 400, the digestateis transferred to the digester 500 in step 1120. In step 1130, gases arecollected from the clarifier 300, the biological reactors 350 and 360,the batch reactor 400, and the digester 500 and are diffused through thedigester 500 allowing for agitation of the contents of the digester 500and further processing of the gases. In step 1140, the gases from thedigester 500 are collected and are used in powering the heat source 600or other generators and/or recirculated through the digester 500.

With respect to FIG. 16, another embodiment of a batch reactor 1400 isshown. The reactor 1400 is similar to the batch reactor 400 of FIGS.6A-9. As shown in FIG. 16, the reactor 1400 also may be a multi-chamberreactor providing a serpentine flow path for the digestate suppliedthereto similarly to the batch reactor 400 as represented by arrows 430in FIG. 7. In particular, the reactor 1400 includes a plurality oflongitudinal flow chambers 1402, 1406, 1408, 1410, 1412 arranged in aserpentine configuration and separated by partition walls 1413, 1415,1407, 1411, respectively. In embodiments, the chambers 1402, 1406, 1408,1410, 1412 may be arranged in any configuration providing for fluidcommunication therebetween (e.g., serially interconnecting the flowchambers 1402, 1406, 1408, 1410, 1412).

The reactor 1400 may include drainage chambers 1404 and 1414 forcollecting settled solids and recirculating unprocessed digestate. Thedrainage tank 1404 is in direct fluid communication with the chambers1402 and 1406, such that the digestate flows form the tank 1402 throughthe tank 1404 and into the tank 1406. The chambers 1402 and 1406 areseparated from the chamber 1404 by flow control mechanisms 1415 and1417, respectively. The flow chambers 1406 and 1408 are separated by aflow control mechanism 1419. The drainage tank 1414 is in direct fluidcommunication with the chambers 1408 and 1412, which are separated byflow control mechanisms 1416 and 1418, respectively. The flow chambers1408, 1410, 1412 are also separated by flow control mechanisms 1420 and1421, respectively. Similarly to the first and second flow controlmechanisms 312 and 316, the flow control mechanisms 1415, 1417, 1416,1418, 1419, 1420, 1421 may also be flow control valves or hydraulicallyactuated sluice gates.

Although the present disclosure described various stages of anaerobicdigestion taking place within various components of the system 100,namely, the clarifier 300, the batch reactor 400, and the digester 500,in embodiments, the reactor 1400 may be configured to carry out multipledigestion processes therein. In particular, the reactor 1400 may includemultiple microorganisms within one or more of the flow chambers 1402,1406, 1408, 1410, 1412, each of which is equipped with the flow controlmechanisms 1415, 1417, 1416, 1418, 1419, 1420, 1421 and circulationloops 402 a, 406 a, 408 a, 410 a, 412 a, and 402 b, 406 b, 408 b, 410 b,412 b allowing for regulation of temperature.

In embodiments, pH and ORP conditions within each chamber 1402, 1406,1408, 1410, 1412 may also be regulated. With respect to FIG. 16, aplurality of pH and ORP probes 1472, 1474, 1476, 1478, 1480 are disposedwithin each of the flow chambers 1402, 1406, 1408, 1410, 1412. The pHand ORP probes 1472, 1474, 1476, 1478, 1480 are substantially similar tothe probes 702, 704, 706 described above with respect to FIG. 5 and arecoupled to the logic controller 802 and the chemical supply tanks 720 a,722 a, 724 a, 726 a. The probes 1472, 1474, 1476, 1478, 1480 measure thepH and ORP within the chambers 1402, 1406, 1408, 1410, 1412 and thelogic controller 802 adjusts the pH and ORP within each of the chambers1402, 1406, 1408, 1410, 1412 to a desired level as described above.

Any number of the chambers 1402, 1406, 1408, 1410, 1412 may include oneor more of the microorganisms utilized in the system 100. Inembodiments, the flow chamber 1402 may include hydrolyticmicroorganisms, the flow chamber 1406 may include acidogenicmicroorganisms as described above with respect to the clarifier 300. Theflow chamber 1408 may include acetogenic microorganisms as describedabove with respect the batch reactor 400. The chambers 1410 and 1412 mayinclude methanogenic microorganisms as described above with respect tothe digester 500. In further embodiments, the chambers 1402, 1406, 1408may include acetogenic microorganisms and the chambers 1410 and 1412 mayinclude methanogenic microorganisms. Various microorganisms may bedeposited on the digestion substrate 440 as described above with respectto the batch reactor 400 as shown in FIG. 8.

The temperature, pH and ORP within the chambers 1402, 1406, 1408, 1410,1412 may be substantially the same as within the clarifier 300 (e.g.,receptacles 302, 304, 306), the batch reactor 400, and the digester 500based on the type of microorganisms and/or digestion stage occurringtherein. In embodiments, where hydrolytic microorganisms are utilizedwithin any of the chambers 1402, 1406, 1408, 1410, 1412, the temperaturemay be from about 25° C. to about 50° C., in embodiments from about 30°C. to about 40° C., and in further embodiments from about 35° C. toabout 38° C.; the pH may be from about 3 to about 10, in furtherembodiments from about 5 to about 9, and in yet further embodiments fromabout 6 to about 8; and the ORP may be from about −50 mV to about +50mV, in further embodiments from about −400 mV to about 0 mV, and in yetfurther embodiments from about −200 mV to about −100 mV.

In embodiments, where acidogenic microorganisms are utilized within anyof the chambers 1402, 1406, 1408, 1410, 1412, the temperature may befrom about 10° C. to about 100° C., in embodiments from about 30° C. toabout 80° C., in further embodiments from about 35° C. to about 75° C.,in yet further embodiments from about 40° C. to about 60° C.; the pH maybe from about 3 to about 10, in embodiments from about 5 to about 9, infurther embodiments from about 6 to about 8; and the ORP may be fromabout −50 mV to about +50 mV, in embodiments about −400 mV to about 0mV, in further embodiments from about −200 mV to about −100 mV.

In embodiments, where acetogenic microorganisms are utilized within thechambers 1402, 1406, 1408, 1410, 1412 the temperature may be from about25° C. to about 50° C., in embodiments from about 30° C. to about 40°C., and in further embodiments from about 35° C. to about 38° C. The pHfrom about 3 to about 10, in embodiments from about 5 to about 9, infurther embodiments from about 6 to about 8 and ORP from about −50 mV toabout +50 mV, in embodiments about −400 mV to about 0 mV, in furtherembodiments from about −200 mV to about −100 mV. In embodiments, wheremethanogenic microorganisms are utilized within the chambers 1402, 1406,1408, 1410, 1412 the temperature may be from about 25° C. to about 60°C., in embodiments from about 30° C. to about 40° C., in furtherembodiments from about 35° C. to about 38° C. The pH from about 3 toabout 10, in embodiments from about 5 to about 9, in further embodimentsfrom about 6 to about 8 and ORP from about −50 mV to about +50 mV, inembodiments about −400 mV to about 0 mV, and in further embodiments fromabout −200 mV to about −100 mV.

The flow control assembly 800 of FIGS. 13 and 14 may also be configuredto operate with the reactor 1400. As shown in FIG. 16, one or more ofthe first plurality of gas ports 804-808 and the like may be coupled tothe chambers 1402, 1406, 1408, 1410, 1412 to sample gases generatedtherein. The sampling measurements are transmitted to the logiccontroller 802, which then outputs the data to a user and/orautomatically controls the flow of the digestate and/or gases throughthe reactor 1400. In embodiments, the controller 802 may be coupled tothe flow control mechanisms 1415, 1417, 1416, 1418, 1419, 1420, 1421 tocontrol the flow of the digestate. The controller 802 also periodicallysamples gases as described with respect to the system 100, and transportthe gases between the chambers 1402, 1406, 1408, 1410, 1412, which maybe interconnected via various gas piping (not shown).

Transportation of gases between chambers 1402, 1406, 1408, 1410, 1412allows for removing gases that are generated in one portion of thereactor 1400 to another portion of the reactor 1400 where such gases areused as reactants. In embodiments, the chambers 1402, 1406, 1408 maygenerate hydrogen gas during hydrolysis, acidogenesis, and acetogenesisreactions that occur therein and the hydrogen gas is used duringmethanogenesis process within the chambers 1410 and 1412 as describedabove. Thus, supplying the hydrogen gas to the chambers 1410 and 1412from the chambers 1402, 1406, 1408 provides for more efficientutilization of the reaction byproducts. The reactor 1400 may also becoupled to the emergency vent 860, the flare burners 850, and the gastake-off 830 for further use at the heat source 600 and other uses asdescribed above with respect to FIGS. 13 and 14.

FIG. 17 illustrates an anaerobic digestion control system 1700 thatcontrols a multi-stage batch or semi-continuous batch process forconverting biomaterial into gas. The anaerobic digestion control system1700 includes the logic controller 802, e.g., a programmable logiccontroller (PLC), which is electrically coupled to various flow controlmechanisms and sensors distributed throughout the digestion system 100.

The digestion control system 1700 also includes the control interface712 described above, which is in communication with the logic controller802. The computer system 712 may communicate with the logic controller802 using any known communications protocol, such as Ethernet TCP/IP,Modbus, or Fieldbus. The control interface 712 may include a server(e.g., the server 1801 of FIG. 18A) and a monitor (e.g., the userinterface 1802 of FIG. 18A) connected to the server through which a usercan monitor and control the digestion control system 1700. The servermay be configured as a terminal services machine that allows forconcurrent client sessions and remote access via a wired or wirelessconnection. In this configuration, an operator may remotely access theserver through any device connected to the Internet to view and controlthe processes described above as well as troubleshoot or makemodifications to the digestion control system 1700.

The digestion control system 1700 includes multiple systems that arecontrolled by the logic controller 802. These systems include a flowcontrol system, which includes a movement control system 1701 and adirectional control system 1711, a temperature control system 1721, apressure sensing system 1731, a totalization system 1741, and an energycontrol system 1751. In general, the flow control system includes afirst flow control mechanism that controls the flow of material throughthe digestion system 100 and a second flow control mechanism thatcontrols the flow of at least one chemical agent to the material.

As described in more detail below, the pressure sensing system 1731, thetotalization system 1741, and the temperature control system 1721include sensors that sense one or more properties of the material, e.g.,biomaterials and gases, flowing through the digestion system 100. Theone or more properties of the material may include ORP, pH, temperature,pressure, composition, and combinations thereof. The logic controller820 may control the flow control system based on the one or moreproperties of the material. The movement control system 1701 and/or thedirectional control system 1711 operate to move and direct biomaterialsand gases through the digestion system 100 based on feedback from thepressure sensing system 1731 and the totalization system 1741. Thetemperature control system 1721 ensures that the biomaterials aremaintained at optimal temperatures for the production of gases.

The movement control system 1701 and the directional control system 1711include flow control mechanisms that vary the flow and direction ofbiomaterials and/or gases through the digestion system 100, which mayinclude the influent collection tank 200, the first and secondbiomaterial intake receptacles 302, 304, the biological reactors 350,360, the batch reactor 400, the digester 500, or any combinationsthereof.

As shown in FIG. 17, the movement control system 1701 includes a solidmovement control subsystem 1702, a gas movement control subsystem 1704,a material movement control subsystem 1707, hydraulic pump controlsubsystem 1706, and chemical pump control subsystem 1708. The controlsubsystems 1702, 1704, 1706, 1707, 1708 are controlled by the logiccontroller 802 via the movement control panel 1705. The movement controlpanel 1705 may include relays, switches, communication lines, and otherinterfaces through which the logic controller 802 controls the controlsubsystems 1702, 1704, 1706, 1707, 1708.

FIG. 18A illustrates an embodiment of the movement control system 1701of FIG. 17. The logic controller 802 is coupled to a server 1801 via anetwork connection 1803. A user interface 1802 is coupled to the serverto allow an operator to access the server 1801 and the logic controller802. The movement control panel 1705 is coupled to the digital outputs1805 b of the logic controller 802 to receive commands from the logiccontroller 802. The movement control panel 1705 distributes thesecommands to the control subsystems 1702, 1704, 1706, 1707, 1708.

The gas movement control subsystem 1704 may include controllers 1814a-b, the blowers 865, 870 of FIG. 1, which are controlled by thecontrollers 1814 a-b, and sensors 1824 a-b, which sense operationinformation about the blowers 865, 870 and transmit the sensed operationinformation to digital inputs 1805 a of the logic controller 802. Thesensed blower operation information may include status and faultinformation. The material movement control subsystem 1707 may includecontrollers 1817 a-n, the pumps 205, 352, . . . , 555 of FIG. 1, whichare controlled by the controllers 1817 a-n, and sensors 1827 a-n, whichsense operation information about the pumps 205, 352, . . . , 555 andtransmit the sensed operation information to the analog inputs 1807 a ofthe logic controller 802. The sensed pump operation information mayinclude motor load (e.g., current load), status (e.g., actual speed andover-speed fault), leakage (e.g., when the oil case seal breaks), andtemperature (e.g., actual temperature and over-temperature fault).

The hydraulic pump subsystem 1704 may include controllers 1816 a-n,hydraulic pumps 1806 a-n, which are controlled by the controllers 1816a-n, and sensors 1826 a-n, which sense operation information about thehydraulic pumps 1806 a-n and transmit the sensed operation informationto digital inputs 1805 a of the logic controller 802. The sensedhydraulic pump operation information may include status, fault, leakage,and over-temperature information. The chemical pump subsystem 1704 mayinclude controllers 1818 a-d, the chemical pumps 720 a-d of FIG. 5,which are controlled by the controllers 1818 a-d, and sensors 1828 a-n,which sense operation information about the chemical pumps 720 a-d andtransmit the sensed operation information to digital inputs 1805 a ofthe logic controller 802. The sensed chemical pump operation informationmay include motor load (e.g., current load), status (e.g., actual speedand over-speed fault), leakage (e.g., of a manifold or a line), andtemperature (e.g., actual temperature and over-temperature fault).

Referring again to FIG. 17, the directional control system 1711 includesa mixer control subsystem 1712, a gas flow control system 1714, ahydraulic gate control subsystem 1716, and a material flow controlsystem 1718. The control subsystems 1712, 1714, 1716, 1718 arecontrolled by the logic controller 802 via the directional control panel1715. The directional control panel 1705 may include relays, switches,communication lines, and other interfaces through which the logiccontroller 802 controls the control subsystems 1712, 1714, 1716, 1718.

FIG. 18B illustrates an embodiment of the directional control system1711 of FIG. 17. The logic controller 802 is coupled to a server 1801via a network connection 1803. A user interface 1802 is coupled to theserver to allow an operator to access the server and the logiccontroller 802. The directional control panel 1715 is coupled to thedigital outputs 1805 b of the logic controller 802 to receive commandsfrom the logic controller 802. The directional control panel 1715distributes these commands to the control subsystems 1712, 1714, 1716,1718.

The mixer control subsystem 1712 may include the mixing valves 612 a,612 b, . . . , 618 of FIG. 4, which are controlled by the logiccontroller 802 via the directional control panel 1712. The mixer controlsubsystem 1712 may provide feedback, such as position and statusinformation, to the digital inputs 1805 a of the logic controller 802.The gas flow control system 1714 may include the gas valves 852, 853, .. . , 895 of FIGS. 13 and 14, which are also controlled by the logiccontroller 802 via directional control panel 1712. The gas flow controlsystem 1714 may also provide feedback, such as position and statusinformation, to the digital inputs 1805 a of the logic controller 802.

The hydraulic gate control subsystem 1716 may include the hydraulicgates 416, 418, 418 of FIG. 4, which are controlled by the logiccontroller 802 via the directional control panel 1712, and sensors 1836a-c, which sense operation information about the hydraulic gates 416,418, 418 and transmit the sensed operation information to digital inputs1805 a of the logic controller 802. The sensed hydraulic gate operationinformation may include position and status information (e.g.,open/closed status). The material flow control system 1718 may includethe liquid valves 312, 316, 321 a-b, 522, 525-527, 702 c, 704 c, 706 cof FIG. 5, which are also controlled by the logic controller 802 viadirectional control panel 1712. The material flow control system 1718may also provide feedback, such as position and status information, tothe digital inputs 1805 a of the logic controller 802.

In some embodiments, the controllers 1814 a-b, 1816 a-d, 1817 a-n, 1818a-d of the movement control system 1701 include variable frequencydrives (VFDs). The controllers 1817 a-n control the rate of materialflow based on level sensor data (e.g., data from the level sensors 492,494, 496 of FIG. 4) and/or based on valve and/or gate modulation data(e.g., percent that the liquid valves 312, 316, 321 a-b, 522, 525-527,702 c, 704 c, 706 c of FIG. 5 and/or the hydraulic gates 416, 418, 418of FIG. 4 are opened or closed). In other embodiments, the controllers1814 a-b, 1816 a-d, 1817 a-n, 1818 a-d include an electromechanicallimit switch that limits the speed of the pumps or blowers to a speedthat gives the most efficiency.

The controllers 1816 a, . . . , 1816 n control hydraulic pumps 1806 a-n,which, in turn, drive gates, such as the hydraulic gates 416, 418, 420,to control the flow of material between reactors or to control therecirculation of material. The controllers 1817 a-n may control the rateof material flow based on the pump speed (e.g., measured in RPM) and/orthe percent of maximum pump speed over a specified time period.

The gas flow control system 1714 may include controllers (not shown),such as VFDs, which drive the gas valves 852, 853, . . . , 895 tomodulate or vary the rate of gas flow between reactors. The controllers1814 a-b drive the blowers 865, 870 to vary the rate of gas flow betweenreactors based on pressure and temperature, which, in turn, are based onthe position of the gas valves, e.g., the gas valves 852-859 of FIG. 13.

In general, the hydraulic gate control subsystem 1716 and the materialflow control subsystem 1718 include flow control mechanisms thatrestrict or allow the flow of material to and from reactors, and betweenreactors. The logic controller 802 controls the modulation, the completeopening, and the complete closing of these flow control mechanisms tocontrol the flow of biomaterial. Biomaterial is retained within areactor when the flow control mechanism is closed. Depending on the sizeand shape of the flow control mechanism between reactors and the sizeand shape of the each reactor, vigorous mixing of biomaterial can beachieved by partially or fully opening flow control mechanisms. Inembodiments, the flow control mechanisms include valves and gates.

The orientation of two reactors and the slope and void levels of thereactors may be designed to direct digestate material towards or awayfrom a pump while the opening of the valves or gates achieveshomogeneity of digestate material within a reactor or between reactors.

The valves or gates can remain open or closed to achieve a volumesetpoint within a reactor that is greater than a volume in anotherreactor or a differential volume setpoint between reactors so thatbiomaterial may be exchanged between reactors more vigorously during aperiod between the opening and closing of the valves or gates withoutthe operation of the material pumps. The material pumps may initiateboth before and after the period between the opening and closing of thevalves or gates so that the material pumps can contribute to therecirculation of a particular fraction of the digestate.

In general, the directional control system 1711 may control thefollowing processes: opening valves to facilitate the outflow ofmaterial from a reactor, opening valves or gates to facilitate inflow ofmaterial from another reactor, closing valves to restrict the outflow ofmaterial from a reactor, closing valves to restrict the inflow ofmaterial from a another reactor, initiating start-stop signals for thematerial pumps, and modulating speed signals for the material pumps.

Material is retained within a reactor when a valve or gate is closed.The rate of material transfer from one reactor to another, the rate ofcomplete evacuation of material from one reactor to another, or the rateof complete evacuation of material from the digestion system can bemodified by changing the size and shape of the valves, gates, and/orpiping between two reactors and the size and shape of each reactor.

In embodiments, two reactors that exchange biomaterial may be designedwith slopes and may be disposed at different elevations so that specificvolumes of digestate within a reactor can be transferred to anotherreactor without the operation of a pump. The slopes and/or elevationdifferences between reactors and the orientation of the material pumpwith respect to the reactor can modify the direction of material flowtowards or away from a pump so that the rate of digestate movement(including any fractions of the digestate within a reactor) can bemodified.

Specific volumes re-circulated within a receptacle and transferred to orfrom a receptacle can be achieved through flow meter monitoring.Specific volumes of digestate can be moved over a specific period oftime by modulating pump speeds during periods of material movement. Thelogic controller 802 may control the flow of material and gas betweenreactors based on retention time and a change in volume, e.g., asdetermined by a difference in level sensor measurements.

The logic controller 802 and the flow control system, which includes themovement control system 1701 and the directional control system 1711,control the processes described above for preparing biomaterial for thedigester 500 and/or the batch reactor 400 (where it is prepared to exitthe digestion system 100) and for moving digestate through the digester500 and/or the batch reactor 400. In embodiments, the logic controller802 and the flow control system may control processes described above asfollows.

With reference to FIG. 1, in a loading mode, biomaterial (e.g.,agricultural waste) may be gravity fed into the influent collection tank200. This may occur each day in the normal course of a farm operation.The loading mode may operate automatically as biomaterial is added tothe influent collection tank 200. An operator may also toggle a loadingmode button in the control interface 712 to start and stop the loadingmode. In embodiments, when the operator turns off the loading mode, thepump 206 may not turn on regardless of the status of the level sensor465, unless the pump 206 is controlled manually. As used herein, theterm “level sensor” refers to any sensor that provides information as tothe volume of gas or biomaterial within a receptacle. As describedherein, the level sensor may include a pressure sensor or a conductivitysensor positioned within a receptacle to indicate when material orliquid reaches the level of the conductivity sensor.

When the loading mode is enabled and the level sensor 465 senses a highlevel of biomaterial within the influent collection tank 200, the logiccontroller 802 starts pump 206 to pump the biomaterial from the influentcollection tank 200 into the first biomaterial intake receptacle 302.The logic controller 802 may run the pump 206 until the level sensor 465senses a low level of biomaterial in the influent collection tank 200. Aliquid flow meter 252 may be coupled to the pump 260 to track the totalvolume of biomaterial introduced into the digestion system 100. Thelogic controller 802 may be configured to automatically stop theoperation of the pump 206 if the second flow control mechanism 316 isopen or if the level sensor 465 indicates that the first biomaterialintake receptacle 302 is already at full capacity. The operator maychange pump 206 to manual mode at any time and turn off pump 206 duringoperation of the clarifier 300 when additional influent is not desired.The operator can also turn off the loading mode via the controlinterface 712.

As described above, before the flow control system transfers the firstbiomaterial to the digester 500 or the batch reactor 400, the rawbiomaterial is processed to achieve a desired consistency in the firstand second biomaterial intake receptacles 302, 304. The flow controlsystem pumps the first biomaterial into the first biomaterial intakereceptacle 302 and/or deposits the second biomaterial, e.g., silage, inthe second biomaterial intake receptacle 304 via a biomaterialprocessing system 2000, which is illustrated in FIG. 20. The flowcontrol system can achieve the desired consistency by mixing the firstbiomaterial with previously processed first biomaterial from thedigester 500 and/or by processing the first biomaterial with therecirculation chopper pump 314.

In embodiments, the flow control system pumps previously processed firstbiomaterial from a biological reactor, e.g., biological reactor 360, tothe first biomaterial intake receptacle 302. The biomaterial processingsystem 2000 performs a screening and grinding process on the secondbiomaterial before it is deposited into the second biomaterial intakereceptacle 304. An operator may view the status of and control thebiomaterial processing system 2000 via the control interface 712.

The biomaterial processing system 2000 includes a hopper 2001, a mixer2012, a mixer gate 2014, an auger 2016, and an auger gate 2018. Thebiomaterial processing system 2000 also includes a hydraulic pump 2024,a variable frequency drive 2032, and a scale 2034 coupled to the logiccontroller 802. The scale 2034 measures the weight of biomaterial addedto the hopper 2001 and provides the weight measurements to the logiccontroller 802. The hydraulic pump 2024 drives the mixer gate 2014, theauger 2016, and the auger gate 2018 according to commands received fromthe logic controller 802. The variable frequency drive 2032 controls themotor 2022 based on commands received from the logic controller 802.

The biomaterial processing system 2000 includes multiple rollers 2002a-g that are rotatably coupled to two opposing walls of the hopper 2001.The biomaterial processing system 2000 also includes a chain 2005 thatis operably coupled to the rollers 2002 a-g to rotate the rollers 2002a-g. Before the biomaterial processing system 2000 starts, an operatorprovides a weight setpoint to the logic controller 802 to set the amountof second biomaterial to add to the second biomaterial intake receptacle304. In some embodiments, the operator may enter a stop weight setpointvia the control interface 712 to set the amount of second biomaterialthat should remain in the hopper after second biomaterial is added tothe second biomaterial intake receptacle 304. For example, if the hopper2001 contains 1500 lbs. of the second biomaterial and the operator wantsto add 1200 lbs. of the second biomaterial to the second biomaterialintake receptacle 304, the operator would need to enter a stop weightsetpoint of 300 lbs via the control interface 712.

When the logic controller 802 receives a start command, the logiccontroller 802 provides a command signal to the VFD 2032, which drives amotor 2022. The motor 2022, in turn, drives a mixer or auger 2012 andthe motion of the chain 2005. The mixer 2012 mixes and circulates silagethat is input to the hopper 2001 via the input port 2003.

After a predetermined period (e.g., one second) the logic controller 802issues a command to the hydraulic pump 2024 to open the mixer gate 2014and to start the auger 2016. After another predetermined period (e.g.,one second), the logic controller 802 issues a command to open the augergate 2018 so that the processed silage can be deposited into the secondbiomaterial receptacle 304. As the hopper 2001 empties, the weight ofthe second biomaterial within the hopper 2001 decreases.

When the weight of the second biomaterial measured by the scale 2034reaches a weight set point (or the operator presses a stop button viathe control interface 712), the logic controller 802 initiates thefollowing stop sequence: (1) the logic controller 802 closes the augergate 2018; (2) when it is confirmed the auger gate 2018 is closed, thelogic controller 802 stops the auger 2016; (3) after a predeterminedperiod (e.g., one second), the logic controller 802 issues a command toclose the mixer gate 2014; and (4) after another predetermined period,the logic controller 802 issues a command to the controller 2032 to stopthe mixer 2012.

Referring again to FIG. 1, when it is necessary to add digestate to thebiological reactor 360, the logic controller 802 opens liquid valves 321b, 321 c and closes liquid valve 321 a so that digestate can flow fromthe digestate receptacle 306, through the liquid valves 321 b, 321 c andthe liquid flow meter 322, and into the biological reactor 360. Inembodiments, the liquid valves 321 a, 321 b, or any two valves in a “T”configuration, may be replaced with a three-way valve.

If the liquid level within the biological reactor 360 as measured by thelevel sensor 366 reaches a high-level setpoint, the logic controller 802closes the liquid valve 321 b to prevent overfill of the biologicalreactor 360. When the logic controller 802 determines that the volume ofdigestate provided to the biological reactor 360 has reached apredetermined volume setpoint based on liquid flow data from the liquidflow meter 322, the logic controller 802 closes liquid valves 321 b, 321c and opens liquid valve 321 a.

After digestate has been provided to the biological reactor 360, thelogic controller 802 may enable recirculation of the product in thebiological reactor 360 either automatically or in response to theoperator selecting a button on the control interface 712. Whenrecirculation is enabled, the logic controller 802 issues a command tostart the recirculation pump 362, which pumps product out of and backinto the biological reactor 360. When a recirculation cycle is complete,the logical controller 802 issues a command to stop the recirculationpump 362.

When recirculation is enabled, the logic controller 802 may continuouslycycle between periods of recirculation and non-recirculation. Theduration of the recirculation and non-recirculation periods may be setvia the control interface 712. In embodiments, the periods may be set toresult in eight ten-minute periods of recirculation per day. If theliquid valves 321 c-d are open before a recirculation period, the logiccontroller 802 may pause recirculation. If the liquid valves 321 c-d areopen during a recirculation period, the logic controller 802 may stoprecirculation.

When it is necessary to transfer processed product from the secondbiological reactor 360 to the first biomaterial receptacle 302, thelogic controller 802 opens the liquid valve 321 d and starts the pump362. When the logic controller 802 determines that the level ofprocessed product within the second biological reactor 360 falls below apredetermined low-level setpoint based on data from the level sensor366, the liquid valve 321 d is closed. An operator can initiate transferfrom the second biological reactor 360 to the second biomaterial intakereceptacle 304 via a button on the control interface 712.

With reference to FIG. 5, when biomaterial is ready to be transferredfrom the second biomaterial intake receptacle 304 to the firstbiomaterial intake receptacle 302, the logic controller 802 starts thepump 314 and runs it at a speed determined by a pump speed setpoint. Thelogic controller 802 also moves liquid valve 522, which is a three-wayvalve, to a first position. The logic controller 802 runs the pump 314until a predetermined period set by the operator elapses.

Biomaterial, especially solids, that is deposited into the secondbiomaterial receptacle 304 can be processed using the chopper pump 314.The operator can manually start processing biomaterial within the secondbiomaterial intake receptacle 304 by selecting a suitable button via thecontrol interface 712. Alternatively, the logic controller 802 canautomatically start processing biomaterial. In either manual mode orautomatic mode, the logic controller 802 starts pump 314 and runs it ata speed determined by a pump speed setpoint programmed into the logiccontroller 802. The logic controller 802 also moves liquid valve 522 toa second position to allow biomaterial within the second biomaterialreceptacle to recirculate via fluid line 521. This process runs for apredetermined period set by the operator. When the process is complete,pump 314 shuts down and liquid valve 522 reverts back to the firstposition, which allows the chopper pump 314 to pump biomaterial into thefirst biomaterial receptacle 302.

As described above, during normal operation, digestate continuouslyflows from the digester 500, through the digester pump station 550,through the digestate receptacle 306, and back to the digester 500 in adigester circulation mode. The control interface 712 may include acirculate button that may be toggled to start and stop the digestercirculation process.

Referring again to FIG. 1, when the digester circulation process starts,the logic controller 802 opens liquid valve 321 a, closes liquid valve321 b, starts and ramps the speed of the digestate receptacle pump 322to a desired speed setpoint (e.g., 75.5%). The logic controller 802 alsostarts pump 555 and automatically adjusts its speed based on a PIDcontrol algorithm that maintains the digestate level in the digestatereceptacle 306 at a predetermined operating level setpoint (e.g., a 20%level) based on feedback from the level sensor 396. When the level ofdigestate in the digestate receptacle 306 reaches or exceeds apredetermined high level, the logic controller 802 causes the pump 555to slow down. Conversely, when the level of digestate in the digestatereceptacle 306 falls below a predetermined low level, the logiccontroller 802 causes the digester pump 555 to speed up to maintain thepredetermined operating level setpoint.

In some embodiments, if the level of digestate in the digestatereceptacle 306 reaches or exceeds a high-level setpoint, the logiccontroller 802 shuts down the digester pump 555. If the level ofdigestate falls below a low-level setpoint, the logic controller 802shut down the digestate receptacle pump 322. When an operator manuallydeselects the digester circulation mode via the control interface 712,the logic controller 802 closes the liquid valve 321 a, opens the liquidvalve 321 b, and shuts down the digester pump 555 and the digestatereceptacle pump 322.

After biomaterials are processed within the first and second biomaterialreceptacles 302, 304, e.g., recirculated within the second biomaterialreceptacle 304, transferred between the first and second biomaterialreceptacles 302, 304, and/or transferred from the second biologicalreactor 360 to the second biomaterial receptacle 304, the flow controlsystem transfers all of the processed first and second biomaterials,e.g., the processed influent and silage, from the second biomaterialreceptacle 304 into the first biomaterial receptacle 302.

Referring again to FIG. 5, in some embodiments, the logic controller 802closes the gate or valve 312, moves the valve 522 to a first position toallow the processed first and second biomaterials to flow into the firstbiomaterial receptacle 302, starts the chopper pump 314, and ramps thespeed of the chopper pump 314 up to a desired speed setpoint. When thelevel sensor 394 senses that the biomaterial level within the secondbiomaterial receptacle 304 has reached a predetermined low level, thelogical controller 802 stops the chopper pump 314, maintains the gate312 in the closed position, and maintains the valve 522 at the firstposition.

Referring again to FIG. 1, once the second biomaterial receptacle 304has been emptied, the logic controller 802 initiates the transfer of thebiomaterials contained in the first biomaterial receptacle 302 to thedigestate receptacle 306 by starting the pump 322 and ramping up itsspeed to a desired speed setpoint (e.g., 100%). When the level sensor396 senses that the digestate level within the digestate receptacle 306has reached a low-level setpoint, the logic controller 802 opens thegate or valve 316 between the first biomaterial receptacle 302 and thedigestate receptacle 306, which allows the biomaterial in the firstbiomaterial receptacle 302 to immediately flow through the gate 316 andinto the digestate receptacle 306.

In embodiments, the floor of the digestate receptacle 306 may bedisposed below the floor of the first biomaterial receptacle 302 to forma step between the receptacles 302, 306. Thus, when the logic controller802 opens the gate or valve 316, biomaterial flows from the firstbiomaterial receptacle 302, down the step, and into digestate receptacle306 to achieve mixing of the biomaterial without using pumps. When thelevel sensors 392, 396 both sense a material level that is at alow-level setpoint, the logic controller 802 closes the gate 316 andstops the pump 322.

In some embodiments, the logic controller 802 simultaneously controlsthe transfer of biomaterial from the first biomaterial receptacle 302 tothe digestate receptacle 306 and the circulation of digestate throughdigester 500. In these embodiments, the logic controller 802 runs thepump 555 at a minimum speed and runs the pump 322 at a greater speed(e.g., 75.5%). As a result, digestate is transferred from the digestatereceptacle 306 to the digester 500 at a slow rate, but when the transferof biomaterial from the first biomaterial receptacle 302 to thedigestate receptacle 306 is complete, the normal process of circulatingdigestate through the digester 500 automatically resumes, allowing thespeed of the pump 555 to vary based on the digestate level measured bythe level sensor 396 disposed within the digestate receptacle 306.

As described above, the first biological reactor 350 may be a continuousfermentation reactor used to grow and store microbes that are used bythe digester 500. At times, a portion of the digestate in the digestatereceptacle 306 is transferred to the first biological reactor 350 tosustain the microbes. Also, the first biological reactor 350 providesdoses of microbes to the second biomaterial receptacle 304 depending onthe demand for microbes.

When it is necessary to add digestate to the first biological reactor350, the logic controller 802 opens liquid valve 321 f and closes liquidvalve 321 g during the digester circulation process so that digestatecan flow from the digester 500, through the pump station 550, liquidvalve 321 f, and liquid flow meter 326, to the first biological reactor350. If the liquid level measured by the level sensor 356 within thefirst biological reactor reaches a high-level setpoint, the logiccontroller 802 closes the liquid valve 321 f to prevent overfill of thefirst biological reactor 350. When the logic controller 802 determinesthat the volume of digestate provided to the biological reactor 360 hasreached a predetermined volume setpoint based, for example, on liquidflow data from the liquid flow meter 326, the logic controller 802closes liquid valve 321 f and opens liquid valve 321 g.

After digestate has been provided to the biological reactor 350, thelogic controller 802 may enable recirculation of the product in thebiological reactor 350 either automatically or in response to theoperator selecting a button on the control interface 712. Whenrecirculation is enabled, the logic controller 802 issues a command tostart the recirculation pump 352, which continuously pumps product outof and back into the biological reactor 360. When a recirculation cycleis complete, the logical controller 802 issues a command to stop therecirculation pump 352.

When recirculation is enabled, the logic controller 802 may continuouslycycle between periods of recirculation and non-recirculation. Theduration of the recirculation and non-recirculation periods may be setvia the control interface 712. In embodiments, the periods ofrecirculation and non-recirculation may be set to result in eightten-minute periods of recirculation per day. If the liquid valve 321 eis open before a recirculation period, the logic controller 802 maypause recirculation. If the liquid valve 321 e is open during arecirculation period, the logic controller 802 may stop recirculation.

When it is necessary to transfer processed product from the firstbiological reactor 350 to the second biomaterial receptacle 302, thelogic controller 802 opens the liquid valve 321 e and starts the pump352. When the logic controller 802 determines that the level ofprocessed product within the first biological reactor 350 falls below apredetermined low-level setpoint based on data from the level sensor356, the liquid valve 321 e is closed. An operator can initiate transferfrom the first biological reactor 350 to the second biomaterial intakereceptacle 304 via a button on the control interface 712.

Referring again to FIG. 5, when the logic controller 802 determines thatthe biomaterial in the digestate receptacle 306 has finished processing,the logic controller opens liquid valves 321 b, 525 allowing digestateto flow to the batch reactor 400. A volume set point is set in the logiccontroller 802 for the volume of digestate to be transferred from thedigestate receptacle 306 to the batch reactor 400. When the digestateflows from the digestate receptacle 306 to the batch reactor 400, itflows through a liquid flow meter 322.

If the digestate level measured by the level sensors 492, 494, 496within the batch reactor 400 reaches a high-level set point, thedirectional control system 1711 issues a high-level alarm and closes thevalves 321 b, 525 to prevent overfill of the batch reactor 400. If thedigestate level within the batch reactor 400 reaches the high-level setpoint, an operator can readjust the volume setpoint to a value below theactual totalized flow as measured by the flow meter 322 or increase thehigh-level setpoint and reset the high-level alarm to allow digestateflow to proceed to completion.

When the flow meter 322 determines that the volume of digestate hasreached a predetermined volume setpoint, the logic controller 802 closesvalves 321 b, 525. The digestate may remain in the batch reactor untilthe operator provides further input via the control interface 712.

An operator may manually start or stop recirculation of the biomaterialin the batch reactor 400 via a button on the control interface 712. Whenrecirculation starts, the valve 525 is opened and the pump 465 isstarted. When recirculation is complete, the valve 525 is closed and thespeed of the pump 465 returns to the previous setpoint speed.

In some embodiments, the flow control system will continuously cyclebetween periods of recirculation and non-recirculation. The duration ofthe recirculation and non-recirculation periods may be programmed via auser interface. The recirculation cycles may be programmed to occurmultiple times each day. For example, recirculation may occur in eightten-minute periods distributed throughout each day. The flow controlsystem may pause recirculation if the valves 321 b, 525 are openedbefore recirculation begins. The movement control system 1701 may stoprecirculation if the valves 321 b, 525 are opened during a recirculationperiod.

In the batch reactor load mode, a predetermined volume of digestateflows into the batch reactor 400. The batch reactor load mode mayautomatically start after all or a portion of the digestate in the batchreactor 400 is transferred to the digester 500 or elsewhere.Alternatively, the operator can start the batch reactor load mode byselecting an appropriate button via the control interface 712.

In the batch reactor load mode, the two-way valve 521 is opened and thetwo-way valve 523 is closed to stop the flow of digestate from thedigestate receptacle 306 to the digester 500. Then three-way valve 525is opened, which allows digestate to flow from the digestate receptacle306 to the batch reactor 400. When the liquid flow meter 325 fluidlycoupled between the digestate receptacle 306 and the batch reactor 400indicates that the predetermined volume of digestate has been reached,the logic controller 802 stops the loading process by closing valve 521,opening valve 523, and closing valve 525.

The flow control system may prevent the batch reactor loading processfrom starting if a level sensor 492, 494, 496 indicates a high digestatelevel within the batch reactor 400 or if the control valve 704 c isopen. Once the batch reactor loading process is started, the controlvalve 704 c is maintained closed until the loading process is complete.The logic controller 802 may pause the batch reactor loading process byclosing the valves 521 and 525 and opening the valve 523 if the levelsensor indicates a high digestate level. The batch reactor loadingprocess may resume when the digestate level drops below the highdigestate level.

In the batch reactor recirculation process, digestate is pumped by pump524 from the second portion 415 of the batch reactor 400, through valve525, to the second portion 413 of the batch reactor 400. In someembodiments, the digestate is also pumped through a dry pit pumpstation. The batch reactor 400 is filled with plastic media describedabove that could become clogged. The control system may be configured todetect clogged media when there is a large difference between the fluidlevel within the first portion 413 of the batch reactor 400 and thefluid level within a drainage chamber of the batch reactor 400 (e.g.,the drainage chamber 414 of FIG. 6A).

The operator can set a recirculation speed and an allowable differencebetween the fluid level in the first portion 413 and the fluid level inthe drainage chamber 404. The operator can also manually start and stoprecirculation by toggling a recirculation button in the graphical userinterface. In some embodiments, the recirculation process may includeopening valve 525 to allow digestate to flow from the second portion 415to the first portion 413, starting the pump 514, and ramping up thespeed of the pump 524 to a speed setpoint. When recirculation iscomplete, valve 525 is closed and the pump 524 is shutdown.

When recirculation is enabled, the logic controller 802 controls theflow control system to continuously cycle between periods ofrecirculation and non-recirculation. The duration of recirculation andnon-recirculation periods can be set by the operator. If no duration isset by the user, the control system may use a default setting, such aseight ten-minute periods of recirculation per day.

In some embodiments, the logic controller 802 may control flow controlmechanisms, e.g., the liquid valves 321 a, 321 b and the digestatereceptacle pump 322, to simultaneously provide digestate to the batchreactor 400 and the digester 500. The logic controller 802 may vary theposition of the liquid valves 321 a, 321 b to vary the flows ofdigestate to the batch reactor 400 and the digester 500.

The logic controller 802 may selectively operate the flow controlmechanisms (e.g., the blowers 865, 875 or gas valves 852-859) in eithera manual mode or an automatic mode. In the manual mode, an operator canselectively issue commands to operate the control devices through a userinterface (e.g., a SCADA display). The operator commands may supersedeprocesses that have not yet finished except for those operator commandsthat would cause irreversible damage to the control devices or otherequipment. For example, in manual mode, an operator may turn on a pumpto fill a tank that is already full, but cannot turn on the pump if aleak is detected or if a pump is in an over-temperature condition. Inautomatic mode, the logic controller 802 controls the control subsystemsbased on feedback from the sensors described herein.

When gas is trapped within a reactor, the pressure and composition ofthe gases are used by the logic controller 802 to control the transferof a specified volume of gas to another reactor to modify the rate ofreaction in each or both reactors.

With reference to FIG. 13, when the gas in the reactors achieves aspecified pressure and composition, the logic controller 802 enables thetransfer of specified volumes of that gas to down stream processingand/or to a gas storage unit 880 to prevent unfavorable conditions inthe reactors. The logic controller 802 operates appropriate gas flowcontrol mechanisms (e.g., the gas valves 852-859 and blowers 865, 870)to avoid the transfer of gas between two or more reactors that are notcomplimentary or supplemental to each other.

As described above, the flow control system, which includes the movementcontrol system 1701 and the directional control system 1711, controlsthe flow of gas by actuating gas valves, blowers, or the combination ofthe two. In particular, the directional control system 1711 may controlthe following processes: opening gas valves (e.g., the gas valves852-859 of FIG. 13) to facilitate the outflow of gas from a reactor,opening the gas valves to facilitate the inflow of gas from anotherreactor, closing the gas valves to restrict the outflow of gas from areactor, and closing the gas valves to restrict the inflow of gas fromanother reactor. The movement control system 1701 may control thefollowing processes: starting and stopping the blowers (e.g., theblowers 865, 870 of FIG. 1) and varying the speed of the blowers.

During operation, gas is exchanged between reactors having differentpressures. The directional control panel 1712 actuates gas valves 1714and the movement control panel 1705 actuates appropriate gas movementsubsystems 1704 to transfer gas from a reactor having a first pressureto a reactor having a second pressure lower than the first pressureuntil the two reactors return to a point within a specified differentialpressure range. The control algorithms executed by the logicalcontroller 820 uses pressure data and/or gas composition data from thechromatograph 820 to prevent gases from exchanging between reactorsuntil a setpoint gas composition and/or setpoint pressure are reached.

Referring again to FIG. 13, gas volume data may be calculated based onthe gas flow data generated by the gas flow meters 823-829 or the gaspressure data generated by the gas pressure sensors 833-839 and 841. Thegas volume data may be monitored during the exchange of gas betweenreactors to maintain the pressure and/or gas composition within eachreactor within a desired setpoint range.

If an event occurs requiring gas evacuation for all low pressure andhigh pressure reactors and/or requiring a high pressure gas storage unit(e.g., the gas storage unit 880 of FIG. 880) to exchange gas with a lowpressure reactor, the logic controller 802 controls the flow controlsystem to cause gas to flow between reactors or among multiple reactors.

The logic controller 802 controls the gas flow control mechanisms basedupon upstream and downstream measurement signals within the digestionsystem including pressure, temperature, and vacuum. The setpoints andsetpoint ranges associated with these measurement signals are programmedinto the logic controller 802 so that the gas flow control mechanisms(e.g., blowers) are controlled to start and stop at periods prior to orduring: pressure swing changes between reactors, evacuation (e.g.,reactor or flare), storage gas recirculation, and gas take off for heatand power generation.

Referring again to FIG. 13, when the logic controller 802 determinesthat (1) gas within a reactor has reached a predetermined gascomposition based on information from the gas chromatograph 822, (2) aretention period has elapsed, and (3) the gas pressure as measured bythe pressure sensors 843-849 has reached a pressure set point, the logiccontroller 802 includes PID control loops 803-809 that control thetransfer of all or a portion of volatile material by actuatingappropriate gas valves 852-859.

As illustrated in FIGS. 17 and 18D, the totalization system 1741includes conductivity meters 1742, gas flow meters 1744, liquid flowmeters 1746, and a totalization control panel 1745, which is coupled toeach of the meters 1742, 1744, 1746. The logic controller 802 usestotalization data generated by the totalization system 1741 to determinethe total energy potential of material in the digestion system 100. Thelogic controller 802 may control the flow control system, which includesthe movement control system 1701 and the directional control system1711, based on the determined total energy potential of material in thedigestion system 100. The flow control system may control the amount ofgas transferred between reactors, the amount of gas re-circulated withina reactor, the amount of gas converted to heat, the amount of gasconverted to electricity, the amount of gas flared, or combinationsthereof based on the determined total energy potential of material inthe digestion system 100.

The totalization system 1741 may also include a scale (e.g., the scale2034 of the biomaterial processing system 2000 of FIGS. 20A and 20B)that provides weight information about the material in the digestionsystem 100. The logic controller 802 may also use the weight informationto determine the total energy potential of the material in the digestionsystem 100.

As described above, the conductivity meters 1742 may be disposed in eachof the reactors, in the fluid lines between reactors, or in the fluidline connected to the chromatograph 820. The conductivity meters 1742measure how strongly digestate materials oppose the flow of electriccurrent based on ORP described above.

The conductivity measurements are used to control various flow controlmechanisms (e.g., valves) that enable the transfer of digestate betweenreactors, the flow control mechanisms that drive the movement ofdigestate, the gates that control the retention and movement ofdigestate material, the valves that select chemicals, and the chemicalpumps (e.g., peristaltic pumps) that deliver selected chemicals to thedigestate.

In general, during a retention time within a particular reactor, theconductivity meters, which include ORP and pH sensors, take measurementsfor a predetermined number of periods during: digestate recirculationwithin a single reactor, material recirculation between reactors,digestate transfer between reactors, and flushing a reactor with othermaterials to remove residuals.

The logic controller 802 determines whether a previous or currentretention time is too short to achieve a desired ORP and/or pH range. Ifit is determined that the previous or current retention time is tooshort, the flow control mechanisms (e.g., hydraulic gates 416, 418, 420)are maintained in a closed state to retain biomaterials within areactor.

As illustrated in FIG. 5, the logic controller 802 also controls theaddition of chemicals by simultaneously adjusting the position of thechemical valves 702 c, 704 c, 706 c and actuating one or more chemicalpumps (e.g., peristaltic or positive displacement pump) 720 b, 722 b,724 b, 726 b to modify (advance, slow down, or neutralize) a particularreaction to maintain the ORP and/or pH levels of the biomaterial withina desired range. The logic controller 802 controls the amount ofchemicals that are added to the reactors by monitoring and controllingthe speed of the chemical pumps 720 b, 722 b, 724 b, 726 b.

The logic controller 802 also controls material recirculation byoperating valves and pumps, e.g., liquid valve 525 and material pump 465of FIG. 5, based on the ORP and pH measurements. In embodiments, thespeed of the material pump 465 and the material rate of turn over ismonitored and controlled to achieve homogeneity within each reactor. Thelogic controller 802 may perform the chemical addition and materialrecirculation processes simultaneously or sequentially.

The logic controller 802 also controls the transfer of material byopening hydraulic gates 416, 418, 420 to a desired open position toachieve a desired amount of biomaterial transfer. The hydraulic gates416, 418, 420 may be opened to a partially-open position by controllingthe amount of oil that is delivered to the hydraulic gates via themanifold of a hydraulic pump. The logic controller 802 may also commandthe hydraulic gates 416, 418, 420 to open completely to achieve vigorousmixing via a surge and flush process. The material pumps 416, 418, 420and chemical addition pumps 720 b, 722 b, 724 b, 726 b may be operatedsimultaneously or sequentially to obtain a desired amount of biomaterialat a desired conductivity level in any reactor.

After all processes governed by ORP and/or pH sensors are completed,subsequent ORP and/or pH measurements are taken to ensure quality. Whena specific ORP and/or pH has been achieved, the logic controller 802concludes that a cycle is complete.

In embodiments, the totalization system 1741 may further include a totalorganic carbon analyzer, the gas chromatograph 820 of FIG. 13, or both.The total organic carbon analyzer measures volatile organic carbon(POC), total organic carbon (TOC), total nitrogen (TN), or combinationsthereof. The total organic carbon analyzer may be coupled in series withthe chromatograph 820 of FIG. 13, i.e., in line with the gas flow to thechromatograph 820. The measurement data from the total organic carbonanalyzer and/or the gas chromatograph 820 may be used in the same way asthe measurement data from the ORP and/or pH sensors to provide feedbackto control various processes of the digestion system

Referring again to FIG. 17, the totalization system 1741 also includesliquid flow meters that measure the rate of material movement andconfirm that specified volumes of material have been transferred to areactor. Physical characteristics of all material types are determinedby K-Factor analysis and are factored into the totalization system 1741to accurately control the amount of biomaterial transferred betweenreactors, the amount of material re-circulated, and the amount ofresidual biomaterial retained within the digestion system.

When raw influent is available, the downstream processing in theclarifier 300 or the batch reactor 400 may require a specified volume ofraw influent. For example, when the digestion system 100 is operated asa batch process and the batch reactor 400 has completed a biomaterialprocessing cycle or is nearing completion of a biomaterial processingcycle, the batch reactor 400 may specify a desired amount of digestateto be provided by the clarifier 300 to keep the batch reactor 400 full.In this case, the liquid flow meter 322 measures the amount of digestatethat is transferred from the clarifier 300 to the batch reactor 400 tomake sure that the batch reactor 400 is not under- or over-filled.

In a semi-continuous batch process, the liquid flow meter 322 may beused to control the flow of digestate that is provided to the batchreactor 400. In some embodiments, the logic controller 802 may speed upthe production of digestate to meet the needs of the batch reactor 400by heating the biomaterial in the clarifier (e.g., injecting steam intothe biomaterial).

The logic controller 302 may factor in the carrying capacity (i.e.,total volume versus a specified maximum volume) of a reactor, which ismeasured by a liquid flow meter 322, and the amount of time required toachieve proper mixing within the reactor to control the transfer ofbiomaterials.

When solids and liquid biomaterials are required in fractions and/or arecompletely uncoupled (i.e., the solids and liquid biomaterials arecompletely separated), the liquid flow meter governs the volume ofliquid biomaterials that are transferred to another location. Inembodiments, a specified volume of liquid biomaterials may be requestedto flush a specified reactor to avoid cross-contamination and/orless-than desirable material accumulation. In this case, a liquid flowmeter, e.g., liquid flow meter 322, is used to control the volume ofdownstream liquid biomaterials (effluent) that is provided to thespecified reactor. As another example, when solids and liquidbiomaterials are wasted as effluent, the liquid flow meter controls thevolume of less-than desirable materials that are transferred from thefinal stage instead of being recycled back upstream for furtherprocessing, including flushing.

The totalization system 1741 also includes gas flow meters (e.g., thegas flow meters 823-829 of FIG. 13) that measure the rate of gas flowand confirm the transfer of specified gas volumes to desired reactors.As described above, the physical specification of all gas types (bothvolatile and non-volatile) are determined by a primary standard (i.e.,calibration gases) using the gas chromatograph 820. The logic controller802 uses the gas-type information and the gas flow meter data toaccurately control the volume of gas transferred between reactors, thevolume of gas re-circulated within a reactor, the volume of gasconverted to heat (e.g., the volume of gas used as fuel for the boiler),the volume of gas converted to electricity, and the amount of gasflared.

As described above, the digestion control system 1700 may furtherinclude a temperature control system 1721 to regulate the temperaturesof the materials within the digestion system. With reference to FIGS. 17and 18C, the temperature control system 1721 includes the logiccontroller 802, which is connected to a network 1803, and a temperaturecontrol panel 1725 a-b electrically coupled to the digital outputs 1805b of the logic controller 802. The temperature control system 1721 alsoincludes multiple fluid temperature sensors 652 a, 652 b, . . . , 658and multiple material temperature sensors 642 a, 642 b, . . . , 648,which are electrically coupled to the analog inputs 1807 a of the logiccontroller 802 via the temperature control panel 1725 b, which includescommunication lines for carrying temperature measurement signals to theanalog inputs 1807 a of the logic controller 802.

Referring now to FIG. 4, the temperature control system 1721 alsoinclude a heat source 600 that supplies heated fluid to the primary ormaster fluid loop 601 and the plurality of secondary fluid loops 602 a,602 b, 602 c, 604 a, 604 b, 606 a, 606 b, 608. The temperature controlsystem 1721 also includes a plurality of circulation pumps 622 a, 622 b,622 c, 624 a, 624 b, 626 a, 626 b, 628 fluidly coupled to the primaryfluid loop 601 and the plurality of secondary fluid loops 602 a, 602 b,602 c, 604 a, 604 b, 606 a, 606 b, 608. The temperature control system1721 also includes a plurality of starters 1815 a-n for starting thecirculation pumps 622 a, 622 b, 622 c, 624 a, 624 b, 626 a, 626 b, 628and a plurality of sensors 1819 a-n for sensing the speed and status ofthe plurality of secondary fluid loops 602 a, 602 b, 602 c, 604 a, 604b, 606 a, 606 b, 608. Digital and analog sensor signals from theplurality of sensors 1819 a-n are fed back to the digital inputs 1805 aand analog inputs 1807 a of the logic controller 802 so that the logiccontroller 802 can control the circulation pumps 622 a, 622 b, 622 c,624 a, 624 b, 626 a, 626 b, 628 via the temperature control panel 1725 abased on the digital and analog sensor signals.

The heat source 600, e.g., a boiler, is fluidly coupled to the primaryfluid loop 601. The temperature of the primary fluid loop 601 may bemeasured by the primary fluid loop temperature sensors 641, 651. Thefirst primary fluid loop temperature sensor 641 is disposed at the heatsource feed and the second primary fluid loop temperature sensor 651 isdisposed at the heat source return. The temperature control system 1721is coupled to a dedicated controller for the heat source 600 andcontrols the heat source 600 by sending an enable or disable signal tothe heat source controller. An operator may also manually enable ordisable the heat source 600 via the control interface 712.

The temperature control system 1721 also includes a chiller heatexchanger 1900, which conditions the gas produced by the digestionsystem 100 before the gas is supplied to the heat source 600 or theelectrical generator 869. The chiller heat exchanger 1900 conditions thegas by, among other things, removing water from the gas. As shown inFIG. 14, the chiller heat exchanger 1900 may be fluidly coupled betweenthe scrubber 832 and the gas blower 870.

FIG. 19 illustrates a chiller heat exchanger 1900 according toembodiments of the present disclosure. The chiller heat exchanger 1900includes a first heat exchanger 1910 and a second heat exchanger 1920.The first heat exchanger 1910 may be a gas-to-gas heat exchanger havingfirst and second inlets 1911, 1912, and first and second outlets 1913,1914. The second heat exchanger 1920 may be a gas-to-liquid heatexchanger having first and second inlets 1921, 1922, and first andsecond outlets 1923, 1924. The first inlet 1911 of the first heatexchanger 1910 is fluidly coupled to the output of the digestion system100. The second heat exchanger 1920, in turn, is fluidly coupled inseries with the first heat exchanger 1910. Specifically, the firstoutlet 1913 of the first heat exchanger 1910 is fluidly coupled to theinlet of the 1921 of the second heat exchanger 1920. Also, the secondinlet 1912 of the first heat exchanger 1910 is fluidly coupled to theoutlet 1923 of the second heat exchanger 1920 via a separator 1930,which is any mechanism that mechanically separates water or other liquidfrom the gas.

In this configuration, the first heat exchanger 1910 receives, at thefirst inlet 1911, gas 1902 produced by the digester 500, which may havebeen processed by the scrubbers 832 (as shown in FIG. 14), and alsoreceives, at the second inlet 1912, gas 1906 that has passed through thesecond heat exchanger 1920. Then, the first heat exchanger 1920 enablesheat transfer from the digester gas 1902 to the gas 1906 output from thesecond heat exchanger 1920. The second heat exchanger 1920 receives, atthe inlet 1921, gas 1904 that has passed through the first heatexchanger 1910 and also receives, at the inlet 1922, cold liquid 1926,such as water from a chiller (not shown) or influent generated by afarm.

In some embodiments, the temperature control system 1721 may include achiller or fluid cooler (not shown) configured to supply cold fluid tothe second heat exchanger 1920 during periods when the outside airtemperature yields less than optimal ambient influent temperatures,e.g., during the summer season.

The second chiller heat exchanger 1920 decreases the temperature of thegas from the digester 500 below its dew point temperature to allowentrained water to fall out of the gas and the first chiller heatexchanger 1910 increases the temperature of the gas 1906 output from thesecond chiller heat exchanger 1920 to a temperature that is within atemperature range that is appropriate for the electrical generator 869and the heat source 600. In some embodiments, the chiller heat exchanger1920 is fluidly coupled to other reactors of the digestion system. Insome embodiments that include a stand-alone batch reactor 400, thechiller heat exchanger 1920 is fluidly coupled to the stand-alone batchreactor 400. A fluid pump may be coupled to the first inlet 1911 of thefirst chiller heat exchanger 1910 to push gas through the chiller heatexchanger. Additionally or alternatively, a blower may be coupled to thefirst outlet 1923 of the second chiller heat exchanger 1920 to pull gasthrough the chiller heat exchanger 1900.

Referring again to FIG. 1, in some embodiments, a material heatexchanger 470 is fluidly coupled between the batch reactor 400 and thedigester 500 for cooling biomaterial that is transferred from the batchreactor 400 to the digester 500. The biomaterial needs to be cooledbecause of the difference in temperature between the biomaterial in thebatch reactor 400 and the biomaterial in the digester 500. The materialheat exchanger 470 may receive cold influent from the farm includinginfluent slurry that has not yet flowed into the first receptacle 302for the pasteurization process. The material heat exchanger 470 enablesheat transfer from the biomaterials in the batch reactor 400 to theinfluent to decrease the temperature of the biomaterial from the batchreactor 400 and to increase the temperature of the influent, bringingthe influent closer to mesophilic temperatures. Material pumps andvalves are fluidly coupled to the material heat exchanger 470 to controlthe flow rate and pressure of biomaterial and influent flowing throughthe material heat exchanger 470 to achieve a desiredmaterial-to-material exposure time and to avoid clogging of the materialheat exchanger 470. As a result, gas is conserved because less gas isneeded by the heat source 600 to heat the influent, pasteurization timeis reduced, and flow rates for influent processing are increased.

The temperature control system 1721 may also include a waste heatrecovery system. The waste heat recovery system may include a waste heatexchanger 475 and waste heat exchanger temperature sensors (not shown)that sense the temperature of both the gas and liquid circulatingthrough the waste heat exchanger 475. Cooling fluid from the electricalgenerator 869 is pumped through the waste heat exchanger 475 and theexhaust gas generated by the electrical generator 869 is pulled throughthe same waste heat exchanger 475. The influent output from the materialheat exchanger 470 is also pumped through the waste heat exchanger 475so that heat is transferred from the cooling fluid and the exhaust gasof the electrical generator 869 to the influent before it is added tothe first biomaterial receptacle 302.

In embodiments, return water of the heat source 600 may also be pumpedthrough the waste heat exchanger 475 to facilitate heat transfer fromthe cooling fluid and exhaust gas of the electrical generator 869 to thereturn water of the heat source 600 to recover the heat wasted by theelectrical generator 869, which is generally inefficient at convertinggas to electricity.

In embodiments, the temperature control system 1721 may include acooling vessel (not shown) that is fluidly coupled between the batchreactor 400 and the digester 500 so that biomaterial can be pumped fromthe batch reactor 400 into the cooling vessel to be cooled by theambient environment before being pumped into the digester 500. Inembodiments, the temperature control system 1721 may include aliquid-to-liquid heat exchanger incorporated into the batch reactor 400.This liquid-to-liquid heat exchanger may regulate the temperature ofdigestate within the batch reactor 400 using materials from otherreactors or receptacles.

With reference to FIG. 4, the heat source 600 maintains the digestate atan optimal temperature for microbes within all reactors to producemethane gas. The heat source 600 may be fueled by methane or othersimilar gases produced by the digestion system 100. Alternatively, theheat source 600 may be powered by electricity produced by the electricalgenerator 869 fueled by the gases produced by the digestion system 100.The heat source 600 may feed a primary fluid loop 601 and multiplesecondary fluid loops 602 a-c, 604 a-b, 606 a-b, 608 disposed in thereactors. The temperatures of the plurality of secondary heat loop maybe controlled with mixing valves 612 a-c, 614 a-b, 616 a-b, 618, e.g.,three-way mixing valves, tied to the primary loop 601.

The temperature of all secondary loop heat exchangers 632 a-c, 634 a-b,636 a-b, 608 a-d in contact with digestate may be limited so that itnever exceeds a high temperature that could damage the digestate (e.g.,122° C.). For this reason, the secondary heat loop temperature may becontrolled separately from the digestate temperature. Each reactorincludes separate temperature sensors 642 a-c, 644 a-b, 646 a-b, 648,652 a-c, 654 a-b, 656 a-b, 658 to measure the temperature of thedigestate and the temperature of the fluid flowing through the secondaryfluid loops disposed in each reactor. The temperature of the fluidflowing through the secondary fluid loops 602 a-c, 604 a-b, 606 a-b, 608are precisely controlled to maintain optimum microbial conditions.

The directional control system 1711 operates together with thetemperature control system 1721 to control mixing valves 1712 (e.g., themixing valves 612 a-c, 614 a-b, 616 a-b, and 618 of FIG. 4) to meter theflow and amount of fluid flowing through the heat exchanger of eachreactor (e.g., the heat exchangers 632 a-c, 634 a-b, and 636 a-b of therespective reactors 302, 304, 306, 413, 415, 350, 360, 500 of FIG. 4).In embodiments, the logic controller 802 and the directional controlsystem 1711 control mixing valves 614 a-b and circulation pumps 624 a-bbased on a temperature setpoint for maintaining optimum microbialconditions within the batch reactor 400, the temperature of thebiomaterial within the batch reactor 400 as measured by the temperaturesensors 644 a-b, and the temperature of the heat exchanger fluid asmeasured by temperature sensors 654 a-b.

A high pressure or compressed fluid source (not shown) provides highpressure fluid to diaphragm valves (not shown) at air and fuel inlets tothe heat source 600 to control the flow of air and fuel provided to theheat source 600 based on the conditions of the heat exchangers 632 a-c,634 a-b, 636 a-b, and 638. The modulation of the mixing valves 612 a-c,614 a-b, 616 a-b, and 618 and the circulation pumps 622 a-c, 624 a-b,626 a-b, and 628 at each heat exchanger 632 a-c, 634 a-b, 636 a-b, and638 are also controlled based on heat exchanger conditions.

When any biomaterial enters a reactor of the digestion system 100, thetemperature sensors 642 a-b, 644 a-b, 646 a-b, and 648 determine itstemperature. Based on temperature setpoints programmed into the logiccontroller 802, differences in return water temperature and biomaterialtemperature control the modulation of the valves 612 a-c, 614 a-b, 616a-b, and 618. In this case, the circulation pumps 622 a-c, 624 a-b, 626a-b, and 628 are initiated to mix the fluid in the primary fluid loop601, which is taken directly from the heat source heat exchanger 631,with the fluid in the secondary fluid loops 602 a-c, 604 a-b, 606 a-b,and 608, until temperature setpoints are achieved.

The logic controller 802 modulates the mixing valves 612 a-c, 614 a-b,616 a-b, and 618 and starts and stops the circulation pumps 622 a-c, 624a-b, 626 a-b, and 628 in series so that biomaterial can be brought to apredetermined temperature during a specified period of time withoutdestroying the surfaces of the lines or pipes of the heat exchangers 632a-c, 634 a-b, 636 a-b, and 638. When the logic controller 802 determinesthat the temperature of the biomaterial falls within a predeterminedtemperature range, it stops the circulation pumps 622 a-c, 624 a-b, 626a-b, and 628. When the logic controller 802 senses heat losses, itstarts another cycle of modulating the mixing valves 612 a-c, 614 a-b,616 a-b, and 618 and starting and stopping the secondary circulationpumps 622 a-c, 624 a-b, 626 a-b, and 628 to reach and maintain thebiomaterial at a predetermined temperature setpoint.

If the temperature control system 1721 detects one or more failureconditions, it may issue an alarm. For example, upon detecting a lowwater level in the heat source 600, the temperature control system 1721may issue an alarm that causes the logic controller 802 to shut down allcirculation pumps 621, 622 a-c, 624 a-b, 626 a-b, 628. After a low wateralarm has issued, the circulation pumps 621, 622 a-c, 624 a-b, 626 a-b,628 may not restart until the low water alarm has cleared and theoperator has manually re-enabled the circulation pumps 621, 622 a-c, 624a-b, 626 a-b, 628 via the control interface 712. Thus, the primarycirculation pump 621 may run constantly in an automatic mode unless thetemperature control system 1721 issues a low water alarm. In someembodiments, the temperature control system 1721 may take no action inresponse to an alarm.

As described above, the logic controller 802 controls the temperature ofthe biomaterial or digestate by operating the circulator pumps 622 a-c,624 a-b, 626 a-b, 628. An operating temperature setpoint is associatedwith each fluid temperature sensor 651, 652 a-c, 654 a-b, 656 a-b, 658.A low temperature setpoint and a high temperature setpoint may beconfigured as deviations from the operating temperature setpoint. Forexample, if a deviation of 0.5° C. is set for the low temperaturesetpoint then the low temperature set point is 36.5° C. If a deviationof 0.5° C. is set for the high temperature setpoint, then the hightemperature setpoint is 37.5° C.

When the temperature of the biomaterial or digestate falls below the lowtemperature setpoint, the temperature control system 1721 starts acorresponding circulator pump 622 a-c, 624 a-b, 626 a-b, 628. Thecirculator pump 622 a-c, 624 a-b, 626 a-b, 628 runs until thetemperature of the material reaches the high temperature setpoint, atwhich point the temperature control system 1721 shuts off the circulatorpump 622 a-c, 624 a-b, 626 a-b, 628. If the temperature of thebiomaterial or digestate rises above the high temperature alarmsetpoint, which is set higher than the high temperature setpoint (e.g.,a deviation of 1 equals 38° C.), or falls below the low temperaturealarm setpoint, which is set lower than the low temperature setpoint(e.g., deviation of 1 equals 36° C.), the temperature control system1721 issues an alarm.

As shown in FIG. 4, the fluid flowing through the secondary fluid loops602 a-c, 604 a-b, 606 a-b, 608 may be controlled by three-way, motorizedmixing valves 612 a-c, 614 a-b, 616 a-b, 618. The mixing valves 612 a-c,614 a-b, 616 a-b, 618 may be controlled by two electrical signals—afirst electrical signal to open the mixing valves 612 a-c, 614 a-b, 616a-b, 618 and a second electrical signal to close the mixing valves 612a-c, 614 a-b, 616 a-b, 618. After the circulator pumps 622 a-c, 624 a-b,626 a-b, 628 start to run, the mixing valves 612 a-c, 614 a-b, 616 a-b,618 are changed to the open position for a predetermined period. Thisprevents one or more of the mixing valves 612 a-c, 614 a-b, 616 a-b, 618from operating when the biomaterial is not heated by a correspondingcirculator pump 622 a-c, 624 a-b, 626 a-b, 628.

The temperature control system 1721 may further include gas temperaturesensors (not shown). In embodiments, the gas temperature sensors may bedisposed near the inlets and outlets of the blowers 865, 870 shown inFIG. 1. Gas temperature data generated by the gas temperature sensorsmay be fed back to the logic controller 802, which controls the blowers865, 870 based on the gas temperature data.

The directional control system 1711 controls the extent to which themixing valves 612 a-c, 614 a-b, 616 a-b, 618 are opened and closed basedon the direction and amplitude of the temperature error signal, i.e.,the difference between a temperature measured by the temperature sensors642 a-c, 644 a-b, 646 a-b, 648, 652 a-c, 654 a-b, 656 a-b, 658 andoperating temperature setpoints.

For example, if the operating temperature setpoint is set to 42° C. andthe temperature is at 42° C., then the logic controller 802 does notissue an open or close command to one or more of the mixing valves 612a-c, 614 a-b, 616 a-b, 618. If the measured temperature starts to dropslightly, the logic controller 802 may issue a command to open one ormore of the mixing valves 612 a-c, 614 a-b, 616 a-b, 618 for a shortperiod. The logic controller 802 may pause for a time delay beforesampling the temperature. If the temperature decreases further in thenext sample, the logic controller 802 may issue a command to open one ormore of the mixing valves 612 a-c, 614 a-b, 616 a-b, 618 for a longerperiod.

Conversely, when the measured temperature of the material increasesabove the operating setpoint, the logic controller 802 may issue acommand to close one or more of the mixing valves 612 a-c, 614 a-b, 616a-b, 618. The amount of time that the logic controller 802 opens orcloses one or more of the mixing valves 612 a-c, 614 a-b, 616 a-b, 618depends on the low and high temperature setpoints and the differencebetween the measured temperature of the material and the operatingtemperature setpoint.

The control devices of the secondary fluid loops 602 a-c, 604 a-b, 606a-b, 608 may be manually disabled by the operator via the controlinterface 712. When the secondary fluid loop 602 a-c, 604 a-b, 606 a-b,608 is disabled, all circulator pumps 622 a-c, 624 a-b, 626 a-b, 628turn off and all mixing valves 612 a-c, 614 a-b, 616 a-b, 618 are forcedclosed. Thus, an operator may disable the secondary heating loops 602a-c, 604 a-b, 606 a-b, 608, for example, to perform maintenance on theprimary and/or secondary fluid loops 601, 602 a-c, 604 a-b, 606 a-b, 608or to quickly shut down one or more of the secondary fluid loops 602a-c, 604 a-b, 606 a-b, 608 in an emergency. The operator may alsomanually control one or more of the circulator pumps 622 a-c, 624 a-b,626 a-b, 628 via the control interface 712.

Referring again to FIG. 17, the temperature control system 1721 may alsoinclude a steam generator 1727. The steam generated by the steamgenerator 1727 may be injected into the first and/or second biomaterialreceptacles 302, 304 to heat the biomaterial contained in the firstand/or second biomaterial receptacles 302, 304. The steam generator 1727is coupled to the heat source heat exchanger 1726, which provides adesired amount of heat to the steam generator 1727. The steam generator1727 is also coupled to the energy logic 1752, which controls the amountof steam generated by the steam generator 1727 and injected into thefirst and/or second biomaterial receptacles 302, 304 based on the amountof material provided to the first and second biomaterial receptacles302, 304.

In some embodiments, the energy logic 1752 may use the weightmeasurements from the scale 2034 of the second biomaterial processingsystem 2000 (see FIGS. 20A and 20B) and the material flow measurementsfrom the flow meter 252 (see FIG. 1) to control the amount of steaminjected into the first and/or second biomaterial receptacles 302, 304.In other embodiments, the energy logic 1752 may control the weight oflow pressure steam that is injected into the first and/or secondbiomaterial receptacles 302, 304 within a predetermined time periodbased on the weight of the material added to the first and/or secondbiomaterial receptacles 302, 304.

With reference to FIGS. 17 and 18D, the digestion control system alsoincludes a pressure sensing system 1731. As shown in FIG. 18D, thepressure sensing system 1731 includes a plurality of pressure sensors841, 843-849, 881-885 that measure the pressure in each of the reactorsand provide pressure sensing data to the logic controller 802 via thepressure sensing panel 1735. The logic controller 802 then translatesthe measured pressure into liquid volume data 1734 and gas volume data1736 (e.g., percent volume within a reactor).

The flow control system, which includes the movement control system 1701and the directional control system 1711, and the temperature controlsystem 1721 use the liquid volume data 1734 and/or the gas volume data1734 to control liquid and/or gas volumes (e.g., to limit liquid volumesand/or gas volumes), material temperature, material flow rate, materialflow direction, retention time, and the number of recirculation cycleswithin the reactors of the digestion system 100. The pressure sensingsystem 1731 also includes a pressure sensor (not shown) for sensing thehigh pressure air volume 1732 of a high pressure fluid source (notshown) that supplies high pressure fluid to drive the valves and gatesof the digestion system 100.

As described above, the movement control system 1701 and the directionalcontrol system 1711 uses the information generated by the pressuresensing system 1731, e.g., the liquid volume 1734, and the gas volume1736, to control the flows of biomaterials and gases. The directionalcontrol system 1711 also controls the delivery of high pressure orcompressed fluid or air for actuating valves and/or gates (e.g., thevalves 312, 316, 321 a-b, 522, 525-527, 702 c, 704 c, 706 c of FIG. 5and the gates 416, 418, 418 of FIG. 4) distributed throughout thedigestion system 100. The valves may include valves for controlling thedirection of biomaterial flows, valves for controlling the direction ofgas flows, valves for controlling the direction of chromatographsampling gas flows, valves for controlling the boiler air-to-fuel ratio,and valves for controlling differential pressure transmitter switches.The digestion system 100 may include an air conditioning unit (notshown) that conditions the air before it is delivered to the valves ofthe digestion system 100. The air conditioning unit may produce airhaving desired levels of humidity, pressure, and particulate matter.

The directional control system 1711 uses the pressure information frompressure sensors 843-849 distributed throughout the digestion system 100to sense leaks. During normal operation, a differential pressuretransmitter switch 884 coupled to the digester 500 opens the evacuationvalve 894 and starts the flare burners 850 of FIG. 14 when the pressurewithin the digester 500 exceeds a predetermined differential pressurevalue. In some embodiments, the evacuation valves, e.g., the primary andsecondary evacuation valves 1411, 1412 of FIG. 11, fail open, i.e.,return to an open position when they are not otherwise actuated.

When limited power or a complete power failure is detected, theevacuation valve to the flares, e.g., the evacuation valve 894 to theflares 850 of FIG. 14, and the valves that control the flow ofbiomaterial and gas are opened.

Referring again to FIG. 17, the energy control system 1751 includesenergy logic 1752, an automatic transfer switch 1754 coupled to theenergy logic 1752, and electrical power converters 1756 (e.g., theelectrical generator 869 of FIG. 1) coupled to the automatic transferswitch 1754. The energy logic 1752 calculates and monitors the totalenergy potential of material within the digestion system 100 andmonitors and controls energy use and gas production by the digestionsystem 100. The energy logic 1752 may calculate total energy potentialbased on Gibbs free energy calculations.

The energy logic 1752 determines overall system efficiency by comparingthe heating and/or electrical loads of the digestion system 100 to theproduction of gas by the digestion system 100. The energy logic 1752 mayalso determine the variance of the loads of the digestion system 100 andcontrol gas production based on the variance of the loads of thedigestion system 100. For example, the energy logic 1752 may send acommand to the logic controller 802 to reduce gas production by thedigestion system 100 when the power or heat loads of the digestionsystem 100 are low and the electrical grid coupled to the electricalgenerator 869 does not have sufficient capacity to accept any powergenerated by the electrical generator 869.

If the amount of gas stored within a gas storage unit 880 reaches apredetermined high level, the energy logic 1752 may evacuate gas fromthe gas storage unit 880 to the environment or to a flare (e.g., theflares 850 of FIG. 14). The energy logic 1752 may use gas flow ratemeasurements, total gas flow measurements, and gas composition analysisof the evacuated gas to control the production of gas within thedigestion system.

If the amount of gas stored within the gas storage unit 880 reaches apredetermined low level, the energy logic 1752 may ignore scheduledflaring protocols and control the run time of the electrical powerconverters 1754 and the heat source 600 (e.g., boiler) accordingly.

If the evacuation system 890 operates with a gas having a specifiedcomposition, e.g., a high-BTU for longer than a specified period, thelogic controller 802 may control the flow control system to reduce theamount of biomaterials loaded into the digestion system 100 based on thedifference between the gas pressure within a gas storage unit 880 andthe atmospheric pressure to avoid high-BTU gas evacuation from the gasstorage unit 880, i.e., wasting. The evacuation system 890 may issue analarm to an operator via the control interface 712 indicating that it iswasting high-BTU gas.

The power converters 1756 may include a primary electrical generator(not shown) and a secondary electrical generator (not shown). If anoperational parameter of the primary electrical generator goes out ofrange, energy logic 1752 operates the automatic transfer switch 1754 toinitiate controlled shut down of the primary electrical generator, startup the secondary electrical generator, and trip master circuit breakersto seamlessly switch from the primary electrical generator to secondaryelectrical generator without failure in the energy control system 1751.

The energy logic 1752 monitors the gas flow, the gas pressure data(which is driven by the blowers), and the gas composition (which isdetermined by the chromatograph 820 and chromatography software 822) toverify that gas production targets are reached for desired gases, e.g.,methane and hydrogen. The energy logic 1752 also uses gas flow rates,gas pressure data, and gas composition data to control the electricalgenerator 869 to meet the electrical loads of the digestion system 100,and the heat source 600 to meet the heat loads of the digestion system100.

While several embodiments of the disclosure have been shown in thedrawings and/or discussed herein, it is not intended that the disclosurebe limited thereto, as it is intended that the disclosure be as broad inscope as the art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

What is claimed is:
 1. A control system for a digestion system, thecontrol system comprising: a flow control system comprising a first flowcontrol mechanism configured to control the flow of a material throughthe digestion system and a second flow control mechanism configured tocontrol the flow of at least one chemical agent to the material; atleast one sensor configured to sense at least one property of thematerial selected from the group consisting of ORP, pH, temperature,pressure, composition, and combinations thereof; a totalization systemconfigured to sense the volume of a material in at least one portion ofthe digestion system; and a controller configured to determine a totalenergy potential of the material based on the sensed volume andcomposition of the material and to control the flow control system basedon the at least one property of the material, the volume of thematerial, and the total energy potential of the material in the at leastone portion of the digestion system.
 2. The control system according toclaim 1, wherein the flow control system comprises a movement controlsystem configured to control the flow rate of material in the digestionsystem and a directional control system configured to control the flowdirection of the material in the digestion system.
 3. The control systemaccording to claim 1, wherein the digestion system includes a clarifier,a batch reactor, and a digester.
 4. The control system according toclaim 3, wherein the flow control system comprises a directional controlsystem configured to control the flow of material from the clarifier tothe batch reactor and the digester simultaneously.
 5. The control systemaccording to claim 3, wherein the clarifier and the batch reactor eachinclude a level sensor and the flow control system is configured totransfer material from the clarifier to the batch reactor based onmaterial retention periods for the clarifier and the batch reactor andmaterial levels measured by the level sensors.
 6. The control systemaccording to claim 3, wherein the digestion system further comprises aninfluent collection tank having a level sensor, the clarifier and thebatch reactor each include a level sensor, and the flow control systemis configured to transfer biomaterial from the influent collection tankto the clarifier based on a material retention period for the clarifierand/or the batch reactor and material levels measured by the levelsensors.
 7. The control system according to claim 1, wherein the flowcontrol system is configured to recirculate material through at leastone portion of the digestion system.
 8. The control system according toclaim 7, wherein the flow control system is further configured tocontinuously cycle between periods of recirculation andnon-recirculation.
 9. The control system according to claim 1, whereinthe controller is configured to control the amount of gas produced bythe digestion system to meet heat loads and electrical loads of thedigestion system or external systems by controlling the flow controlsystem.
 10. The control system according to claim 1, wherein the flowcontrol system is configured to control at least one of the amount ofgas transferred between reactors of the digestion system, the amount ofgas re-circulated within a reactor of the digestion system, the amountof gas converted to heat, the amount of gas converted to electricity, orthe amount of gas flared.
 11. A method of controlling a digestionsystem, the method comprising: sensing at least one property of amaterial in the digestion system, the at least one property selectedfrom the group consisting of ORP, pH, temperature, pressure,composition, and combinations thereof; determining the volume of thematerial and a total energy potential of the material based on thevolume of the material and the composition of the material; controllingthe flow of at least one chemical agent to the material; and controllingthe flow of the material through the digestion system based on the atleast one property of the material, the volume of the material, and thetotal energy potential of the material.
 12. The method according toclaim 11, wherein controlling the flow of the material comprisescontrolling the flow rate of the material and the flow direction of thematerial.
 13. The method according to claim 11, wherein the digestionsystem is selected from the group consisting of a clarifier, a batchreactor, a digester, and combinations thereof.
 14. The method accordingto claim 11, wherein controlling the flow of the material comprisescontrolling the flow of gas from the digestion system to a gas storagevessel, a flare, or an evacuation vent based on at least one of thecomposition of the gas and the pressure of the gas within the digestionsystem.
 15. The method according to claim 11, wherein controlling theflow of the material comprises controlling the amount of gas produced bythe digestion system to meet heat loads and electrical loads of thedigestion system or external systems.
 16. The method according to claim11, wherein controlling the flow of the at least one chemical agentcomprises controlling the flow of the at least one chemical agent basedon at least one property of the material selected from the groupconsisting of ORP, pH, and ORP and pH.